The meteoric rise of Facebook.com is highlighted below from a picture taken from alexa.
Summary of Facebook.com
Facebook.com has swept colleges around the US allowing the possibly to Web site to chat with friends, meet new people, find parties, hook up, gawk, judge and, occasionally, help with academics. It seems that Facebook accepts new members who have an e-mail addresses that ends in ".edu," extension, allowing the site restrict entry to only students. For more information .... read the newstory
or visit the website at Facebook.com