Yeah, DTD would be awesome... Or a 'grow' collection. I'm really hoping that The Behemoth will work on an Alien Hominid port. Apparently they're still thinking about what to do with the iPhone...
A good 2d fast shooter/adventure eg. Heli attack, alias, unreal, alex in danger etc. A good lander type game eg. Starship eleven/seven. A game like gravity ball which was an inventive breakout game. Any of the above would be great. Nice thread!
Not actually Flash games, but the games by Under Clouds Games are pretty darn good, and heck, they're even built for playing on the iPhone, albeit via the Safari browser on the iPhone. There's more details here on another TouchArcade post...
How about Super Mario Flash? Seems like quite a nice little time waster...and possibly the closest we will get to Mario on the iPhone... http://www.andkon.com/arcade/adventureaction/supermarioflashv3/ EDIT: It even has a level editor apparently!
frekin dungeon escape! its awesome http://www.studiohunty.com/dungeon/ and +1 to whoever said insaniquarium and interactive buddy.