If you're in the Austin area and a fan of old school D&D, run, do not walk, to ArmadilloCon at the Renaissance Hotel this Sunday morning or early afternoon. Diesel has his collection of art from his TSR days on display in the art show.
When he told me he was bringing this at GenCon, I thought it was just going to be some of the stuff he did, which would be cool enough. But he's got stuff from a wide range of artists, including Elmore, Otus, and others. He's even got the beholder piece that would become the cover to Greyhawk book of the original brown books (apparently rescued from the trash!). It's an amazing and very cool collection, some it of never released commercially.
The art show is only open from 10 AM to Noon on Sunday, so be sure to get there in those hours to see it. It's a really cool slice of the hobby's history.