PhotoS is a simplistic tool which transforms photographs into Freehand Sketch. You don’t need to have any technical knowledge, just load your photo and hit the “Draw Sketch” button. Ofcource, you can fine tune elements such as line width and detail level, but that’s simple as well.
PhotoS is a shareware, you can download and try it upto 30 conversions, after which you’ll have to buy a license key. Photoshop experts can create better looking sketch, but it needs some time and patience.