As a fan of DC's Elseworlds stories (as well as the Legends of the Dark Knight toy line by Kenner), I could draw Batman in different historical outfits all day. Unfortunately, I'm not that good an artist, so Braveheart Batman and Black Knight Batman aren't really options. But after catching an advance screening of "The Runaways," I started thinking about the 1970s glam rock/punk rock movement, and after briefly debating if it made any logical sense for Batman to do anything in the '70s other than be Batman, I kinda sorta made him the frontman for the Stooges.
I don't know what the other Stooges look like, but I gave Batman Iggy Pop's chiseled abs and skinny jeans. Of course, I instantly regretted not making Batman David Bowie, since then I would at least have an easy pun. ("A Bat Insane," "The Thin White Bruce," etc.) The name "Iggy Pop" doesn't lend itself to Batman-related puns, although I suppose you could call the band "Iggy and the Bruces." And of course he would perform such hits as "I Wanna Be Your Unofficially Sanctioned Vigilante," "Search and Place in Arkham Asylum" and "Lust for Street-Level Justice." Here's a colored version.
Check out the amazing covers for Batman: The Return of Bruce Wayne at DC's The Source.