A Vigorous Batman Auction: Comic artist Frank Miller is credited with revitalizing the Batman franchise. Now he's cashing in. He has consigned two pieces of his artwork — both valued at more than $50000 — to Heritage Auctions for its February 22-24 sales. The book cover art for "Absolute Dark Knight," which Miller says is one of this favorite pieces, will be offered alongside the splash page from "Batman: The Dark Knight Returns," featuring Carrie Kelly, the first female Robin. "It took me years
