I don't have Little Big Planet, but my friend at work was planning to build a custom level to post online, so he asked for some ideas. The basis was "Puzzles," since Little Big Planet levels are typically platformer-based concepts, he thought it would offer something a little more unique. For days I was offering ideas, and he built them.
I invite everyone who plays Little Big Planet to download the level my friend made (which I brainstormed the concepts for most of the puzzles for). His I.D. is CBW2005 and the level is called littlebigpuzzleplanet. It's probably one of the more unique levels you'll find online.
For those who don't know, Little Big Planet is a new release Playstation 3 title.