meh... I wasn't impressed with NFS underground.
Anyway... as far as "must-have" TP2 games? Generally any VGA game is a safe bet. But below is my list of VGA games that I've played on my TP1 and TP2.
Action Platform Puzzle Game
Archibald's Adventures
Card
RealDice Texas Hold-Em The multiplayer is pretty fun. In fact any of those RealDice casino games are great in VGA.
Adventure/RPG
Broken Sword: Shadow of the Templars awesome adventure game with full cinematics and speech. Great to show off.
EA Mobile Clue is another cool/fun game in VGA. Make no mistake, it's only lightly based off the board game. In fact there are other EA mobile titles that are good too... I like Tiger Woods 09 VGA.