Facebook directory at “facebook.com/directory” provides a directory of users who select to make their Facebook profiles public. Facebook creates a preview version of their profile which is accessible to anyone.
H-Online.com has an interesting report by Chris von Eitzen about a Hacker who has written a web crawler which he used to systematically graze through facebook data. He has collected more than 170 million sets of data containing the names and URLs of public profiles. The files do not contain any other personal data such as friend lists, but the links in the profiles can easily be used to send out another crawler to collect other information. The crawler and collected data are available as a 2.8 GB torrent.