In my recent wanderings of the interweb I stumbled upon an awesome online sketching app that is really fun and does a decent job of replicating the look and feel of sketching with some real world mediums. And one of the coolest features is that you can play back an animation of the sketch being created once you are finished.
Check it out! Its good fun. http://sketch.odopod.com/
Here is a little bluebird that I did.