I don't know if you're a big app person, I'm not. I have literally two pages of apps on my iPhone total with no folders to speak of. But there are a few apps I could never live without (ok technically I could live without them but what I'm saying is I'd be very sad. and bored. except I'd probably read a few more books. but that's not the point...) and use all the time. Afterlight is one of them. It's a photo editing software app, and I think it cost a couple of dollars, maybe five at the most. It's so fun to play around with pictures and see how they look with different filters and exposures and textures.
I usually post my edited pictures to my tumblr account, ON WALDEN ROAD, to share there. If you have a tumblr account please share a link in the comments box, I'd love to follow along!