I think Groupon kinda does this for new users (ie, you enter your email, hit next, it scrolls to the left, you pick your city, etc.)

One thing I've found is that if the purpose/value proposition of your product isn't already fairly obvious when a user comes to your site, you should spend more time in marketing the product and educating potential customers instead of trying to attract people who are pretty much clueless about what you do. On one of my web apps, having to sign up was the single most voiced complaint about the site, even though signup literally took less than five seconds.