The hitchhiker's galaxy is ever expanding, but don't panic, there's still time to catch up. Since its opening night as a BBC radio series, Douglas Adams's The Hitchhikers Guide to the Galaxy has taken the form of five bestselling novels, an award-winning television series, record and CD albums, stage productions, a computer video game, a website, nine comics, a feature film, and even a towel set. This Rough Guide encompasses all of those Hitchhiker incarnations,…