The world can never have enough Kitty Pryde and Lockheed artwork, and the nicest one you'll see on the Internet today comes via artist and illustrator Dane Ault. Ault's definitely got range. Give his portfolio a few clicks, and you'll see a Green Lantern with some knockout colors that sits over at the Darwyn Cooke end of the spectrum; but he's also done some fine Swamp Thing and Wonder Woman portraits that look more like the work of J.G. Jones.
Ault handles humor and dramatic poses equally well. The sketches in his deviantART gallery show of a number of approaches, and if they weren't all displayed together, you could swear they were done by two different creators.

Additionally, Mythbusters fans will want to note his Muppet tributes to hosts Jamie Hyneman and Adam Savage. On that note, though, are there any Muppet myths worth testing? Because a Muppet episode of Mythbusters could be mighty awesome.