Old versions of Debian follow:
buzz (release 1.1) rex (1.2) bo (1.3) hamm (2.0) slink (2.1) potato (2.2)
The current DebianStable is woody.
Next stable will be Sarge (probabily at the end of October 2004), but for now is the current DebianTesting, while the new testing will be most likely Etch.
As some know, Sid will always be unstable (DebianUnstable code-named DebianSid).