Vetle's Character papercraft generator (Copy hosted by me so I can tweak it and copy bits of code from it.) (The only change I have made is to put a Google Analytics tracker on it.) (Original released here with suplimental files here)
http://minecraft.net/skin/robothacker.png Replace "robothacker" (my Minecraft username) with your Minecraft username (or someone else's Minecraft username that has a cool skin.) The usernames are case sensitive, to get Notch's you have to use "Notch" with the uppercase "N".
Nova Skin, Awesome 3D skin editor that has a button you can push to get the papercraft version. I'm not affiliated with them, but I love what they did, the 3D skin editor and that they interfaced my papercraft generator into it.