iCloud is a nifty tool for storing photos, but you'll hit that 5GB cap fast. Don't bother paying for more iCloud storage, though - this app will store every photo you have for free.
Shutterfly gives you access to unlimited photo storage for your mobile device. You can even upload pictures from your computer and have the app manage them. If you have a picture you really love, you can post it to Twitter or Facebook right from the app.
You can create photo collages, add filters and fun effects, even order prints.