As a non-smartphone user, of course some people around me had an iPhone with them. I can't really resist myself to 'steal' it from them and touch it, slide it, or maybe licking it.
There was an epic apps/games I tried, Angry Bird.
Not to say it's really good, but the game can't get you bored. Definitely an enjoyable game you can play all day long.
Technically, the game is about Birds-shooting. On each stage, just use a fixed number of bird(s) to take down woods and pig(s?). So epic yet so fun.
Other than that, how can I forget an App that I can't live without it as I mentioned before. It is Twitter apps!
Few Twitter apps are available, but I guess Twitterific and TweetDeck are the best. Type in words, and just TAP on "Tweet" button and everyone know what are you doing! If you're famous, they can even stalk you if your location were exposed on your tweets.
Apple iTunes App Store for iPhone, simply impressive.