Grallery™ (Free) by ustwo™ is a fun way to personalize your iPhone or iPod touch with custom user generated wallpapers. You can browse through the selection of designs and share them with friends.
Grallery makes changing the wallpaper on your iPhone or iPod touch a simple process. You'll have a lot of fun personalizing your device with beautiful and creative backgrounds.
After you launch Grallery you'll find a library of available user generated wallpapers. Browse through the selection to find ones you like, then preview them in full-screen mode. Simply tap the download button on the control bar to add it to your Camera Roll. From there you can set it as your wallpaper, the Lock Screen background, or both.
Grallery has a couple of other interesting features. It provides details about the designer, the idea behind their wallpaper, and a website link where you can check out more of their artistic works. You can also share them through Facebook, Twitter, or e-mail.
The only caveat is it's not designed for the iPad. You can run it on an iPad, but the images are grainy and pixelated.
The Grallery team is constantly updating the library of wallpapers as designers and artists submit them. You might want to check it out each day for new ones. The app is free and so are all of the images in its library.