Adam L. Penenberg has an excellent essay in Wired News: What, Me Register? He tells how he (and others) circumvent the annoying registration requirements of Web sites, mostly news-related ones:
Depending on my mood, I’m a 92-year-old spinster from Topeka whose hobbies include snowboarding, macramé and cryptology; the CEO of a successful high-tech firm in Bumblebutt, New York, whose company has a market capitalization of four cents; or an Alaskan mango grower. What magazines do I read? Soldier of Fortune, Modern Bride, Granta and High Times. Date of birth? Dec. 7, 1941. July 4, 1976. Jan. 1, 1901. My name? Jed Clampett, Mustang Sally or Freddy Fudbuster.
Much more creative than my collection of fake identities, I admit. But I agree with his point completely: I strongly suspect that most of the information people are submitting is bogus, so why perpetrate the fiction? Why annoy everyone to collect dubious information for the sake of advertisers?
Update: See this post for some other suggestions on how to avoid annoying sign-in requirements on Web sites.