The iPhone filters from Photojojo are pretty neat and cheap!
Jelly Phone Filters are keychain sized adapters for your camera phone’s itty bitty lens.
Morph your otherwise low-res snapshots into something of a spectacle with kaleidoscopes, wide angles, and starbursts. Each filter is outfitted with a re-usable gummy ring so you can use it over and over again.
via Jelly Phone Filters.