Help on Games to get.

So far, my library is poor, and I've had my DS Lite for about a year now.

Current Library:

Animal Crossing Wild World

Big Brain Academy

Mario and Luigi: Partners in Time

Give me some suggestions on games to get.

Mario Kart

Castlevania (either POR or DOS)

Club House Games 

those three should keep you busy for a while. 

Final Fantasy 3

Castelvania PoR

Diddy Kong Racing

Mario vs DK 2

 Yoshi's Island DS

Super Mario 64 DS (the controls take a bit of getting used to at first)

Mario Kart DS!!!!!!!

Lunar Knights

Phoenix Wright (both)

Hotel Dusk Room 215

Final Fantasy III

FF3

Castlevania PoR

If you like strategy games, Advance Wars DS is amazing.  I've got over 220 hours of game play on it, and I still haven't done everything.  I prefer Mario Kart over Diddy Kong Racing, but both are good racing games.  The best FPS is easily Metroid Hunters.  I'm nearing 100 hours of gameplay on that one.  As for puzzle games, I suggest Meteos.  Not the disney one; being able to move blocks sideways cheapens gameplay and reduces the strategy and skill needed.  Some people are raving over PuzzleQuest, but I can't comment on that yet as I haven't played it.