I've been noodling around on a hand-me-down iPhone with no service for over a week now and I find a few apps keep me coming back again and again. Over the next week or so, each of us with an iPhone or iPod touch will tell you our favorite or most-used apps.
1. ShoZu - OK, I use this maybe a little less than AirMe, but only because I don't use the iPhone as a cell phone. AirMe is great when you're out and about and need to send a pic instantly (to Flickr, in my case). ShoZu is like AirMe on steroids, minus the instant upload. That's a good thing, in fact. If you're a big fan of blasting your photos and text posts to a bunch of services at once, ShoZu is ideal. There are over a dozen services it'll hook into, and you can set up a "CC" list so whatever you upload pushes to several places at once. We'll put this through the wringer soon and give more details in a full review.
2. Texas Hold'em - Like Steven said, this is a port of the iPod version. But I have to give Apple a lot of credit for showing everyone how to make use of the iPhone's features. Tip the iPhone over and you see a top-down table view, throw your cards into the pot to fold, etc. There's a lot of polish on this and it is much cheaper than playing the real thing with my card sharp buddies (none of whom have mortgages, apparently). Mike Rose notes his one big gripe with this Hold'em, in contrast to the classic iPod version: no way to have your own music play in the background while you rake in the chips.
3. ToDo - From our very own Erica Sadun comes this super-simple app that's just a "to do" list for you GTD or listmaking freaks. Aside from the simplicity of the app itself, the badge on the app icon is really handy if you're trying to stay on top of things and only need a glance to see what is pending. One would think Apple could do this with iCal to-do's, but apparently creating a great poker app is an easier task. Perhaps they can use ToDo as well?
App Store links --
ShoZu and AirMe
[thanks for the copy editing Dave!]