I bookmarked a post on A List Apart earlier this year by the name of "Sign Up Forms Must Die." In the article, author Luke Wroblewski makes a great case for rethinking the placement and overall necessity for sign-up forms.
When planning a customer's initial experience for your web service, think about how you can avoid sign-up forms in favor of gradual engagement.
I've been brainstorming ways to skip the sign-up process for an upcoming project and I was reminded of said article. At the bottom of the page, Wroblewski provides a nice list of best practices to take away.