It's time to admit it. The Nintendo DS is not a graphical powerhouse, and it sometimes has been neglected by publishers around the world while atrocious games for 10-year-old girls hoard the market. However, there are some games out there that deserve a port to the portable console. Some of them use the touch screen to a great extent. Some of them don't - yes, not every SINGLE game for DS has to include half-assed minigames involving the touch screen or even use it at all. Most importantly, on-line multiplayer could be a lot of fun.
5 - Magic the Gathering Online: Even though I'm past my playing years, I believe this could be some fun... as long as players didn't have to pay for the cards. Tapping mana, choosing targets and such could be easily handled with the stylus.
4 - Street Fighter series: I remember playing the Gameboy version (yes, the black and white one) and it run pretty smoothly. I honestly don't see why it couldn't be made.
3 - Fallout 1 and 2: It would be awesome to play this on DS. It would also ride the wave of Fallout 3, which would most likely boost sales.
2 - Diablo 2: Or just any western action RPG for that matter. Nothing fancy, really. Throw in a bunch of items, change the colors and the stats. Make the game in isometric view. The DS would be the perfect system for this.So far I've only found Japanese stuff and below-average dungeon crawlers.
1 - Monkey Island: Or any of the old Lucas Arts games. I can't think of a better format for a revival.
*Bonus: ICO. Heh, if only.