USB camera's are often able to transfer photo's in PTP mode, or acting as a mass storage device.

For PTP, gthumb is convenient (file->import photos).

See also

There is also gphoto2 (command-line) and gtkaw (gui).

DanielGermer was able to make a Panasonic DMC-LC33 work, after simply copying and modifying the Shellscripts from this HOWTO. (usb-camera-howto from Debian Documentation (see also: /usr/share/doc/HOWTO/en-txt/USB-Digital-Camera-HOWTO.gz) I modified the Scripts a little so that they transferred the jpegs directly into a folder of my LinPHA.
The script (can be run as root but not as user) looks like this:

(note that the first DIRPATH does not have the dollar (not like in PHP)).