The experience for new vs. returning users

A number of web services create two entirely separate site experiences for new vs. returning users. The new user experience is typically focused on the benefits of the service and getting people to sign up.

For example, compare the different home page presentations for new vs. existing users on Tastebook. New users are presented with clean, simple page with just three main options: How it Works, Look Inside (a product tour), and Get Started.

Below is the "logged in" version of the Tastebook home page--the starting point for actually using the service.

LinkedIn uses a similar approach, with a super-simple home page for new users:

The advantage of this approach is that it eliminates options that aren't functional for users who haven't yet signed up for the service.  It also makes a crisp distinction between the web site for the product and the product itself (a distinction that exists, of course, for desktop software).