Following Dave Johnson on Twitter is always good value (he's a funny guy), but especially these last few days, as he posted the sketches and commissions he'd done at Dragon*Con over the Labor Day weekend. Plenty more can be found below, including one that's maybe a little NSFW.
(Dave draws a mean Richard Roundtree)
(After visiting his parents, post-convention, Johnson mentioned how tiring the non-stop sketching was. They responded by getting him to draw Spider-Man for their neighbor!)