The DSi is epic win.

I could play with it for weeks without even having any games! (even though I could still play my DS games on it)

I don't even know how long. You can play music, make music, record sound, distort sound, take pictures, mess with pictures, download games, browse the internet...

But you can't play GBA games. So if I ever can afford one, it won't be until I'm done with Drill Dozer (which is very fun BTW).