Today Google adds clip art and line drawings to their image search criteria, in addition to photos and faces.
To restrict your search to either line drawings, clip art, photos, or faces, choose the style criteria from the drop-down on an image results page. (Alternately you can add the right parameter to your search URL to set up a keyword quick search; for line drawings, for example, it's &imgtype=lineart.) Check out a cool example search for Celtic art line drawings. For more Google search fun, check out our top 10 obscure Google search tricks. New search-by-style options for Google Image Search [Official Google Blog]
