If you like shooters, Call of Duty 4 on the DS is pretty great... granted its a reduced graphic port of the console/PC title, but for playing on the go, its one of the best games I've played, which is not slightly ironic since the actual Call of Duty 4 is currently my favorite game.

Another DS suggestion would be Final Fantasy III, as has been mentioned... its great for any and all FF fans... and if you're going to pick that up, you might want to reserve Final Fantasy IV while you're at it (which has also been mentioned), as that remake will hit stores on the 23 of this month (just under 2 weks away). That said, I would stay away from FFXII: Revenant Wings... I loved FFXII, and I love strategy games... but this was niether... yeah the story is fairly good, but throughout the whole of the game I was irritated by the fighting system, and once I completed it, I simply had no care to ever touch the thing again (and thus I turned it into $12 of store credit at GameStop).

Moving on... you should ask yourself what kind of games do you like most... the great thing about the DS is that it has most every type of game... though some titles will be extremely hard to find (like Resident Evil: Dead Silence, a game that has already been recommened and that I would love to get... but I can't find it anywhere), most are pretty good... and some ports are great, even though they have the graphic reduction. Another great port is Lego Star Wars... if you enjoyed those games on the console or if you haven't played them yet, but like Star Wars, pick yourself up a copy of Lego Star Wars: The Complete Saga... its great fun, perfect for portable gameplay.

Well... anyway... there are many more great games out there... I think the best thing would be to go to your local gamestore and take a look at their used DS section... I say used, becasue that way if you happen to pick one you end up hating, you can always bring it back and try again.