This game came out last week, and I'm surprised there hasn't been a thread about it yet. Anyway, Flipnote Studio (AKA Moving Notepad) is a simple animation program for the DSi. It's a fun little thing to play around with, and you can also make some really great animations with it, then upload them to Flipnote Hatena. But what I really find impressive is that they're giving it out for free on the DSi Shop. So if you have a DSi, I reccomend getting it.
Also, here is my page on the Hatena website.