How do people get those cool borders and photo effects when they post iPhone photos to twitter?

I've noticed a lot of cool pictures with cool borders posted from iPhone to twitter and was wondering how people get those borders..... Is there a really good app or something?! Please help!!!! I've been looking everywhere!|||Well I use the Photoshop express app and it has a few frames you can use. Or you can try an app called photo effects which has some really cool effects for you pictures. Both are free as well :)