It's a site that predates Facebook: Facemash used "photos compiled from the online facebooks of nine Houses, placing two next to each other at a time and asking users to choose the “hotter” person"
But I have a feeling you are confusing things and timelines. Perhaps you are remembering the actual hot or not site that did just what you remember while thinking of the facemash or whatever that Zuckerberg made prior to FB that we probably all learned about when we watched The Social Network.