If you're writing web applications, you've probably found that a user registration page is an anathema to new users - they see a registration form, and it's just too much effort to bother filling in, so they leave.
In order to combat this, Dan Fairs has written
django-lazysignup, a Django module that will automatically create a new user for every person who visits your site, which they can later use to create themselves a real account, without losing any of the data that they've used with the site so far.