Hot or Not
Alexa Global Traffic Rank: 16,776
Started in October 2000 by two Silicon Valley engineer friends, this profile photo rating site pulled in over 2 million page views per day within a week of its launch. It inspired many knock-offs; even Mark Zuckerberg threw together his own take, Facesmash, for Harvard students to rate the looks of fellow students. Hot or Not was sold in February 2008 for a rumored $20 million to the owners of the “casual encounters” dating site Ashley Madison, whose motto is "life is short, have an affair."