In September 2007, a file containing around the names, social security numbers, scores, grades, and other information of about 64 students on Scratchpad50.com. The operator of the domain could not be readily identified, so the host and domain registrars were notified. Though the file had already been removed from the site when it was discovered, the information was available until September 18, 2007 through a Google Cache.
You can confirm whether you were affected by this breach by searching for your name at www.ssnbreach.org.
Source: www.ssnbreach.org.