Can people actually now see who views your profile on facebook?

[Beans]

I see all these pages and group sites on facebook claiming that they can send you a notification or something to tell you who has been viewing your profile. Does this actually work? I thought I read somewhere that it was against privacy laws and facebook would never show who's profile you've been looking at. Some application come up on my friends new feed the other day while I was with her, and it was a list of who views your profile and it was a list of 100 people. Can someone explain this to me? I'm not a facebook stalker but it still makes me nervous, and if this all does work can someone tell if you've looked at their profile if you aren't friends with them?