Using a Database/Cookies

After implementing all of this personalization, its wasted if a user goes away, comes back and sees it all gone. Usually sites will store the necessary information in a cookie on the user's machine to keep track of their preferences (and we all know what other little things we can get cookies to do). You can also store all/some of the data in a database of users. You can also use both, one as a back-up or a reference code (for multiple users on the same machine), or behind-the-scenes customization for recommendations etc. If you use it right, you can have a very powerful tool for helping the user as well as spying on them ; )