To "check out". I see what you did thar.
Call of Duty 4 for DS is almost nothing like the real thing, but it's still fun. Phoenix Wright is popular but I never liked it- you might or might not. I could never get into the DS Pokemon games, not sure if it's because I'm older or because they aren't as good.
There's some good homebrew out there too. If you don't have a flashcart, get one, even if you have no intention of using it for games. It can be a handy media player too. Anyway, OpenTyrian DS is a good port of the classic PC game, which I used to love so much and when I saw the DS port I was like *Can'tSayThisOnTV* YEAH WOSHIP. DSDoom is crippled by a bad control layout. Animanatee isn't really a game- it lets you make animations with layers, colours, onion skin, framerate and the ability to save.
I used to play my DS a lot, but then I started using it only for music and videos, and I have an MP3 player now so I don't use it at all. Six months ago I could recommend a lot of games, now not so much.