I posted this a while ago in another area but thought it be worth to repost it especially since I now have an iPhone 5 and can appreciate some of these even more. A few freebies here, but those that cost are well worth it. Camera+ and both Tilt Shift apps are some of my favorites. Also the FREE Photoshop from Adobe is a must.
Even if you don’t use some of these get them when they are cheaper or free, storage on iTunes has no cost and you never know when one of these effects will come in handy. There are other apps too that go along with all these, but that is for another post. I should also add that many of these Apps also work on the iPad which I use as a camera often also. Enjoy!