I have written about mobile phone photography once, with Jason L. Parks pictures, and I will undoubtely share other photos from mobile phones in the future. Nowadays phones have nice photo specs, but the improvements also come from software, and you will understand better how nice pictures can be obtained once through this article.
Features include basics such as crop, rotate, taking pictures (without leaving the app). More fancy effects are present like Warm Vintage, Vignette or Sketch. You can upload your photos to photoshop.com if you open a free account, and you can also send them to facebook or twitter.
A free easy-to-use very efficient app, definitely a must have.
application's site, or this flickr group for examples.
Like the previous one, this app is simple and fast to use. It also can share photos through Twitter, Facebook, mail, Flickr.
100 Cameras in 1 is only available on iPhone ($1.99) right now, but an Android version is being developped.
miniature like photography, this is what this application does. For $0.99 you can put the world in your pocket! Unfortunately this is an iPhone only app.
111 Gigapixels 16 photos panorama. Nice huh? Check this flickr group for examples. Buy Pano for $1.99.