There is actually a really great plug in available for photoshop that will take a photo and make it sketch-like. It is created by Topaz Labs and a website for them is http://www.topazlabs.com/. They offer an unlimited 30 day trail of their product.

The area you are looking for within the program to do is the "Clean" one. Give it a try. I think you might like what all it does.

-Holly