German illustrator Carsten Mell has a great body of work on his site, very neatly arranged into various categories.

Tommy Kane has had a prolific history working in advertising. He also does some fine paintings. Check out his blog for sketches and new work.

Designer and illustrator Izzie Klingels specializes in creating stippled artwork with pens. Her black and white pieces, in particular, bear an elegance more closely related to art photography than illustration.

Manuel Larino has a tidy website that effectively displays his work. Along with the final art, he also has shots of the pieces in use, as well as his pencil sketches (which are amazingly clean).

Oscar Gimenez is indeed the definition of a visual chameleon. His work is amazingly adaptive, and his book displays his accomplishments in different fields, different styles and different media.