Metanet Software has been going over some of the user generated levels from their ninja platformer N++.  

For their first post, they went over imagery:

Above are ten beautiful levels that use tiles in interesting ways. Some are more representative, like the bridge and oil rig levels, which evoke a specific scene or object and build a challenge around it. Some are more functional, like Choose Wisely, which divvies up the level into rectangular rooms. Some are abstract, like c: format, some artistic, like Mona Lisa, and some are kind of a mix of abstract and representational, like Dusk Patrol, which looks kind of like a castle made of blocks.

For the second post, they covered progression, similarity, and difference:

Today we’re taking a look at some levels made by N++ players that come in pairs of two, so we can juxtapose them and see how they relate and where they diverge. (We often make pairs of “sibling” levels that explore the same idea in two different directions, so we think it’s really interesting to see this happening with other level makers.)

I also include a video of a level that plays itself.

Make sure to check our Metanet Softwares tumblr to stay up to date as they check out the user generated content in N++. You can also be featured in their blog post if you buy the game and make a level.  Chances are the TorontoGameDevs.com level will not make their cut though :)