There's something I've been working on, and I was actually planning on getting an RTB server to host it once it was done.
I made a pack of bricks that are for use in platformer-type servers. These include grind rails, bumpers (made flexible using events, can have directional bumpers, targeted bumpers, custom power, etc.), and boosters (also has events for custom power). (it's not relevant, but i plan on releasing these) Everyone I've showed these to has enjoyed them, so I figure they're pretty much done.
I decided I wanted to have a server to show these, so we've started making a challenge/speedrun/playground build for them. If I could still record with Fraps, I would get some video, but all I have are words at the moment. I know the concept of 'challenge' isn't original; the main focus is the usage of the bricks. It's a similar idea to Jetz's climbing pick challenge.