There’s a pretty neat Burger King sponsored site that lets you create a simpsons version of yourself. It starts with uploading a photo, but that seems extraneous, seems like they should just let you play with the different parts and skip the photo part.
It does a pretty good job, it started off looking a lot like me, all I had to do was add glasses and switch the hairstyle.
You can try it out here: Simpsonize Me, though the site has been getting a lot of traffic and is kinda slow right now.