Love this article: http://andrewchen.co/the-highest-roi-way-to-increase-signups-make-a-minimal-homepage-guest-post/ on simple homepages and also the negatives comments to the article. I believe Andrew Chen is right. Stop giving away free stuff - make people sign up before they can use your product, unless you don't really care about sign-ups.
It's a good article and I'm sure if it works for all those major brands it's worth trying. However, it doesn't work for me. I prefer to know more about what a company is, or does, before I sign up. I'll Google them and often not come back. I have way too many emails coming already without more from a site I have to sign up to just to check them out.