I've been doing some marker roughs of monsters this week and having alot of fun. I haven't done this in almost 10 years, but I'm finding its a great medium that suits my personal aptitudes towards drawing in tone. I love the chisel shape of the markers and the ability to work fast and loose. I'm working on manilla paper to get the toned ground alowing for highlights. The guy at the art store recommended a product called FW Acrylic artist's ink, which works great for the whites... much better than guache or graphic white.