Until today, I had no idea that Facebook has a search feature designed to help find family members (or at least those with the same last name).  Available at http://facebook.com/family the search gives you some letters to start off with, or simply start typing in your (or any) name.

Not sure how useful this is, but I think it's neat.  Could this be a legacy feature that just isn't linked to anywhere in the current Facebook design?  Who knows.