Basically it parses the HTML structure of the page and turns it into a set of colour-coded nodes in 2D space. Try looking at this site’s graph (should be complete in <1min), or if you’ve got a lot of spare time, the Beeb homepage. Facebook’s AJAXy interface makes its graph surprisingly simple.

To benefit all users, therefore, we will soon be launching a “profile clean-up” tool. Similar to how your computer’s desktop will remind you to get rid of unused icons, this tool will give users the option to move extra profile boxes to an “extended portion” of their profile. Users can choose to move these boxes; we will recommend that they keep the Friends Box, Mini-Feed, Wall, Basic and Personal Information as well as the top 12 application boxes they have added. At the bottom of the profile will then be a link to “Show Extended Profile”.