Below is a generic ?CloudFormation example that can be re-used for your own templates (namely the Parameters, Mappings and selection of the ami-id in the EC2-Instance are interesting in that regard - The list of instance types should be complete too). The Mappings below Cover Wheezy-7.7 and Jessie as of 2014-10-24. Unfortunately, not all combinations of Region/Hypervisor/VolumeType/Release have an Amazon Image available.

{
        "AWSTemplateFormatVersion": "2010-09-09",

        "Description": "CloudFormation Template for Debian Stable/Testing",

        "Parameters" : {
                "InstanceName"   : {
                        "Description": "Instance name",
                        "Type"       : "String"
                },
                "KeyName" : {
                        "Description" : "SSH Key Name",
                        "Type"        : "String"
                },
                "DebianRelease"     : {
                        "Description"   : "Debian Release, Hypervisor and RootVolume Type (DebianWheezy77PvmEbs, DebianWheezy77PvmInstance, DebianWheezy77HvmEbs, DebianJessieHvmEbs) see: https://wiki.debian.org/Cloud/AmazonEC2Image/Wheezy and https://wiki.debian.org/Cloud/AmazonEC2Image/Jessie",
                        "Type"          : "String",
                        "Default"       : "DebianWheezy77PvmEbs",
                        "AllowedValues" : [ "DebianWheezy77PvmEbs", "DebianWheezy77PvmInstance", "DebianWheezy77HvmEBS", "DebianJessieHvmEbs" ]
                },
                "InstanceBits"      : {
                        "Description"   : "32 or 64 bits",
                        "Type"          : "String",
                        "Default"       : "64",
                        "AllowedValues" : [ "32", "64" ]
                },
                "InstanceType": {
                        "Description": "Instance Type (m1.small, etc. see: https://aws.amazon.com/ec2/instance-types/ and https://aws.amazon.com/amazon-linux-ami/instance-type-matrix/)",
                        "Type": "String",
                        "Default" : "t1.micro",
                        "AllowedValues": [
                                  "t1.micro"
                                , "t2.micro"
                                , "t2.small"
                                , "t2.medium"
                                , "m1.small"
                                , "m1.medium"
                                , "m1.large"
                                , "m1.xlarge"
                                , "m2.xlarge"
                                , "m2.2xlarge"
                                , "m2.4xlarge"
                                , "m3.medium"
                                , "m3.large"
                                , "m3.xlarge"
                                , "m3.2xlarge"
                                , "c1.medium"
                                , "c1.xlarge"
                                , "cr1.8xlarge"
                                , "cc2.8xlarge"
                                , "c3.large"
                                , "c3.xlarge"
                                , "c3.2xlarge"
                                , "c3.4xlarge"
                                , "c3.8xlarge"
                                , "r3.large"
                                , "r3.xlarge"
                                , "r3.2xlarge"
                                , "r3.4xlarge"
                                , "r3.8xlarge"
                                , "cg1.4xlarge"
                                , "g2.2xlarge"
                                , "i2.xlarge"
                                , "i2.2xlarge"
                                , "i2.4xlarge"
                                , "i2.8xlarge"
                                , "hi1.4xlarge"
                                , "hs1.8xlarge"
                                , "hs1.8xlarge"
                        ]
                }
        },

        "Mappings": {
                "DebianWheezy77PvmEbs" : {
                          "ap-northeast-1" : { "32": "ami-970b3a96", "64": "ami-0f0f3e0e" }
                        , "ap-southeast-1" : { "32": "ami-4e20011c", "64": "ami-70220322" }
                        , "ap-southeast-2" : { "32": "ami-0185e83b", "64": "ami-bd87ea87" }
                        , "eu-west-1"      : { "32": "ami-c664cbb1", "64": "ami-9c62cdeb" }
                        , "eu-central-1"   : { "32": "ami-522a1c4f", "64": "ami-4c2a1c51" }
                        , "sa-east-1"      : { "32": "ami-3f7dc922", "64": "ami-a97dc9b4" }
                        , "us-east-1"      : { "32": "ami-0258e26a", "64": "ami-2058e248" }
                        , "us-west-1"      : { "32": "ami-c53d2880", "64": "ami-893c29cc" }
                        , "us-west-2"      : { "32": "ami-677e3157", "64": "ami-df7c33ef" }
                        , "us-gov-west-1"  : { "32": "ami-030e6820", "64": "ami-3d0e681e" }
                        , "cn-north-1"     : {                       "64": "ami-e44ad8dd" }
                },
                "DebianWheezy77PvmInstance" : {
                          "ap-northeast-1" : { "32": "n/a",          "64": "ami-21f6c720" }
                        , "ap-southeast-1" : { "32": "n/a",          "64": "ami-24240576" }
                        , "ap-southeast-2" : { "32": "n/a",          "64": "ami-e386ebd9" }
                        , "eu-west-1"      : { "32": "n/a",          "64": "ami-187fd06f" }
                        , "eu-central-1"   : { "32": "n/a",          "64": "ami-4a2a1c57" }
                        , "sa-east-1"      : { "32": "n/a",          "64": "ami-417eca5c" }
                        , "us-east-1"      : { "32": "n/a",          "64": "ami-bc4af0d4" }
                        , "us-west-1"      : { "32": "n/a",          "64": "ami-4b3e2b0e" }
                        , "us-west-2"      : { "32": "n/a",          "64": "ami-ff7a35cf" }
                        , "us-gov-west-1"  : { "32": "n/a",          "64": "n/a"          }
                        , "cn-north-1"     : { "32": "n/a",          "64": "n/a"          }
                },
                "DebianWheezy77HvmEbs" : {
                          "ap-northeast-1" : { "32": "n/a",          "64": "ami-97f1c096" }
                        , "ap-southeast-1" : { "32": "n/a",          "64": "ami-d822038a" }
                        , "ap-southeast-2" : { "32": "n/a",          "64": "ami-ed87ead7" }
                        , "eu-west-1"      : { "32": "n/a",          "64": "ami-e261ce95" }
                        , "eu-central-1"   : { "32": "n/a",          "64": "ami-482a1c55" }
                        , "sa-east-1"      : { "32": "n/a",          "64": "ami-fd7dc9e0" }
                        , "us-east-1"      : { "32": "n/a",          "64": "ami-a458e2cc" }
                        , "us-west-1"      : { "32": "n/a",          "64": "ami-6f3f2a2a" }
                        , "us-west-2"      : { "32": "n/a",          "64": "ami-af7b349f" }
                        , "us-gov-west-1"  : { "32": "n/a",          "64": "ami-010e6822" }
                        , "cn-north-1"     : { "32": "n/a",          "64": "ami-e64ad8df" }
                },
                "DebianJessieHvmEbs"   : {
                          "ap-northeast-1" : { "32": "n/a",          "64": "ami-33a59432" }
                        , "ap-southeast-1" : { "32": "n/a",          "64": "ami-24381976" }
                        , "ap-southeast-2" : { "32": "n/a",          "64": "ami-cd97faf7" }
                        , "eu-west-1"      : { "32": "n/a",          "64": "ami-d2228da5" }
                        , "eu-central-1"   : { "32": "n/a",          "64": "n/a"          }
                        , "sa-east-1"      : { "32": "n/a",          "64": "ami-f76cd8ea" }
                        , "us-east-1"      : { "32": "n/a",          "64": "ami-62e86d0a" }
                        , "us-west-1"      : { "32": "n/a",          "64": "ami-89d5c0cc" }
                        , "us-west-2"      : { "32": "n/a",          "64": "ami-b39cd383" }
                        , "us-gov-west-1"  : { "32": "n/a",          "64": "ami-9f0f69bc" }
                        , "cn-north-1"     : { "32": "n/a",          "64": "ami-264bd91f" }
                }
        },

        "Conditions": {
        },

        "Resources" : {
                "MyInstance" : {
                        "Type" : "AWS::EC2::Instance",
                        "Properties" : {
                                "SecurityGroups" : [
                                        { "Ref" : "SgTcpSsh" },
                                        { "Ref" : "SgTcpSsl" }
                                ],
                                "KeyName"        : { "Ref": "KeyName" },
                                "Tags"           : [
                                        {"Key": "Name", "Value": {"Ref" : "InstanceName"} }
                                ],
                                "ImageId"        : { "Fn::FindInMap" : [ { "Ref": "DebianRelease" }, { "Ref" : "AWS::Region" }, { "Ref" : "InstanceBits" }  ] },
                                "InstanceType"   : { "Ref" : "InstanceType" },
                                "UserData"       : { "Fn::Base64" : "" }
                        }
                },
                "SgTcpSsh" : {
                        "Type" : "AWS::EC2::SecurityGroup",
                        "Properties" : {
                                "GroupDescription" : "SSH Ingress",
                                "SecurityGroupIngress" : [
                                        { "IpProtocol" : "tcp", "FromPort" : "22", "ToPort" : "22", "CidrIp" : "0.0.0.0/0" }
                                ]
                        }
                },
                "SgTcpSsl" : {
                        "Type" : "AWS::EC2::SecurityGroup",
                        "Properties" : {
                                "GroupDescription" : "SSL Ingress",
                                "SecurityGroupIngress" : [
                                        { "IpProtocol" : "tcp", "FromPort" : "443", "ToPort" : "443", "CidrIp" : "0.0.0.0/0" }
                                ]
                        }
                }
        },

        "Outputs": {
                "MyInstanceInstanceId"       : { "Value" : {        "Ref" :   "MyInstance" } },
                "MyInstanceAvailabilityZone" : { "Value" : { "Fn::GetAtt" : [ "MyInstance", "AvailabilityZone" ] } },
                "MyInstancePrivateDnsName"   : { "Value" : { "Fn::GetAtt" : [ "MyInstance", "PrivateDnsName"   ] } },
                "MyInstancePublicDnsName"    : { "Value" : { "Fn::GetAtt" : [ "MyInstance", "PublicDnsName"    ] } },
                "MyInstancePrivateIp"        : { "Value" : { "Fn::GetAtt" : [ "MyInstance", "PrivateIp"        ] } },
                "MyInstancePublicIp"         : { "Value" : { "Fn::GetAtt" : [ "MyInstance", "PublicIp"         ] } }
        }
}