Hmm, I was going to mention Puzzle Quest: Challenge of the Warlords, but it looks like Puzzle Quest 2 is the sequel.
Overlords: Minions is maze/strategy puzzles with a little bit of fighting - an evil overlord sends out his little impy minions to explore areas, collect items, fight opponents, and use their special talents to bypass obstacles.
Have you played it? Did you have a problem with the touchscreen controls?
Oooh, Peggle. I played the crap out of that on Xbox. That could definitely while away an hour or twelve in 5 minute increments (I play my DS mostly during my commute).