The Faces of Facebook is a project by freelance creative technologist Natalia Rojas (whose previous work includes Volvo's X-Ray App). Rojas has created a site that has organized every single profile picture on Facebook in chronological order, from Mark Zuckerberg onwards. You can just randomly browse it (Rojas has worked out that if you were to take a look at each of them for just one second it would take 36 years, 5 months, 9 days, 6 hours, 46 minutes and 16 seconds of your life), or you can log in with Facebook to see what number you were to sign up, and where your friends are. The latter is an interesting insight into early social media adopters among your peer group, but in case you're worried about privacy, Rojas assures us that no-one's private details are stored by the site.
She also said that access to the site has been intermittent, thanks to a record number of visitors causing server disruptions. So if you don't get through, try again later.