I've got a little battery powered Fender Mustang Mini amp that has a bunch of built in effects, has an aux input for your MP3 player (Or CD,if you choose, but you can get a whole more on a little mp3 player than you can a CD).
It wouldn't do any of the automatic switching around and stuff, but it's small, loud enough, and flexible.
Programmer - An organism that turns coffee into software.
If all your friends are exactly like you, What an un-interesting life it must be.
"A door is what a dog is perpetually on the wrong side of" Ogden Nash