Super Meat Boy, the hit (and joyously punishing) indie platformer, has received a level editor as part of a Steam update that rolled out last night. Whilst it's technically still in beta, this editing suite allows players to create their own levels, chapters and - we assume - challenges that make the original stages look like a walk in the park.
After creating a level, you'll need to complete it in order to set the par time (and to prove that it's actually possible) - and then upload the stage to the Super Meat World portal where it can be downloaded and rated by other players. You can find plenty of tutorials in the official forums.
Note that full chapters (minimum of five levels) can also be created, but you unfortunately won't be able to deploy Warp Zones and bosses. Let us know how you get on! [Team Meat Blog]