Agreed on Meteos! I enjoyed the game when I first got it, but really wasn't into it a lot. Then a few months later I picked it back up and was obsessed. Really fun, really cool game.
Also, Tetris of course. How can anyone not like Tetris? I ended up playing more than I had anticipated and think it was worth every penny.
I enjoyed the heck out of Super Puzzle Fighter II Turbo for the GBA(since it can be played on the DS). Such an awesome game. :)
"I feel like I could take on the whole Empire myself."