Debian on a USB stick
I, just yesterday managed to get a copy of debian sarge bootable from a USB stick. It really was quite a simple proccess in the end. In short; 1) Minimum Deb install on a hard disk, 2) Make and format a fat and a linux partition(or 2 if you want a swap file) on the USB device, 3) Grub for dos into the fat partition, 4) copy the Deb install to the USB linux partition, 5) Set up grub to boot it!
It really is that simple...
Ive also installed later versions of linux(FC7) and Enlightenment too so the whole linux thing took over a bit over the last few days :)