Stalkscan Reveals All Your Facebook Info That's Available Publicly
Despite its creeptastic name, Stalkscan is perhaps best used as a self-audit tool, rather than a way to track someone else. For starters, you need the full link to a person's profile. Enter the profile URL in the search box and the site will give you quick links to a bunch of searches for things like that person's pictures, videos, or likes.
While it sounds scary, all of this information is drawn from public Facebook searches. In other words, if you go to Facebook right now and search for "Pictures of [X person]" you'll get the exact same results as if you click the Pictures link on this site. You'll only see photos that are visible to your privacy settings. So, if you're searching for the profile of someone you're not friends with, your results will be very limited.
This is most useful if you want to discover what others can see about you. I tried it out on my own profile and found pictures that I don't remember from a long time ago. It also gives you links to searches you might not have thought to hide, like future events or places you've been tagged in. If you've never audited your public Facebook info, this is a good place to start.