This week I came across a couple of items all related to the sign up process. First, there is Luke Wroblewski's summary of a survey of sign up forms conducted by Smashing Magazine. Definitely check out the full survey report (part 1 and part 2) as it is interesting to see what most sites do.
Luke also references his own article, Sign Up Forms Must Die, which is an excerpt from his new book on forms, where he promotes "gradual engagement" - allowing users to try out a web service first before having to create an account.
The book: Web Forms Design: Filling In The Blanks.