Check out this very strange website that analyzes a few paragrpahs of your writing and tells you who you write like.
I apparently write like Chuck Palaniuk, a fact I find hilarious and way off target, not that I'd mind writing like the author of Fight Club. I remember hearing him read and talk once, and how how said that he emulates Amy Hemphill, which also seemed like a strange and unlikely comparison to me.
UPDATE: Someone inputted a section of the phone book into this database and was told that they write like Thomas Hardy. So: maybe not such a good judge of authorial influence. Good to know that as of yet, computers can not do a writer's job.