37signals recommends the Hollywood Launch. Release a few hints until the big day, when people flood your site, sent by blog coverage. What happens: They bring the site down. They discover some big bug. You bring the site down for everyone because there was a syntax error. Everyone misunderstood what your product does because your front page wasn't clear enough. They all think it's stupid. The traffic is gone. Hardly any of those users come back. What you should have done all along: the Gmail Launch. Have users from day one. Give it to your friends and family. Keep improving it based on their feedback. Let them invite their friends. Automate the process, giving everyone some invite codes to share. Codes protect against a premature slashdotting. Iterate. Take off the code requirement. People will come across it and become real users. Then build buzz. Have some kind of news hook. With Reddit, we switched from Lisp to Python. Start marketing.