With Sketch Guru you pick a picture from your picture gallery or take a new picture that you turn into a pencil sketch, gouache painting or why not a watercolor. In addition to these, there are ten other effects, such as chalk, 8 bit, raster style similar to cartoons and more. You can share your creations on Facebook, Twitter and Flickr, or send them by regular e-mail.
Download for Android (Free)
An alternative to iPhone is My Sketch (12 kroner)
For Windows Phone there is Sketch Camera (12 kroner, try for free)