Tozzle- This one is a matching game for preschoolers. The phone as a scene in it, such as dinosaurs or fairies. Pieces of the scene are blacked out shapes. Your child drags the full color version from the puzzle piece box to the correct location.
Google- You can control it with your voice. Push the Google app button, speak what you want to find, and it brings up the correct websites. Works pretty good too. In fact, when my computer at work freezes up, I use my iPhone to Google the answers I need.
Wikipedia- Works the same as the website, only faster to get to.
USAA- I have to say, my banks app is the best one I've found. Not everyone can open an account, it caters to the military. I joined when I was still active duty, so I'm in for life. But, back to the app. It rocks! Need to check your balance? You can do that of course. But what makes this one special is the other stuff you can do: transfer money in or out of a mutual fund, get help when you have a car accident (they're mostly an insurance company) and deposit a check, all from your iPhone. Yep, you read that correctly. If I need to deposit a check no need to go to the bank. Whew! They're only branch is in Texas. All I have to do is take a picture of it with my iPhone and it's in my back immediately. Playing with the accident section of the app just now I realized it has a built in flashlight. Kinda cool.
Facebook- As a Facebook kind of person, I like being able to access it from my iPhone.
SciFiWire- Get the latest news on the SciFi front. A must in this house.
Fandango- Find your movie and purchase tickets, all while stuck in traffic on the way to the movies.
Local TV stations- A couple of our local stations have apps where you can check the latest news.
Lego Photo- You can turn an existing picture into a Lego-ized picture. Or take a new one. The old photo isn't messed up, the new Lego version saves as a new picture.
There are lots of others, but these are some of my favorites. I have also found apps with pick up lines for chicks (really funny) or one to tell you if you've drank too much to drive.