Whatever the Gameboy Advance uses. GBA games generally have awesome music, probably because by the time of the GBA there had been a lot of collective experience with making awesome music on sound chips.

I don't have one yet, but this is something I'd like to get into (chiptunes).

The Yamaha YM2608!

only iconic one I can think off at the top of my head is the sound blaster 16

puni

The one that makes the noises come out of my computer

Kellogs corn flakes? .-.

uhhhhhhh does the Roland SC-55 count?

One that has a good crunch

Professional Tracker, even if it's not strictly chip tune