Have you subscribed to a group which will send you regular messages from them advising you of events. You should unsubscribe to stop this happening.
Also, people may be finding you through people who's list you are on etc. You should then set your profile, so only people in your immediate list can see you exist.
You can do this by hovering your cursor on the "Settings" tab which is on the right hand side of the blue Facebook Banner, in between your name and the logout tab. Click on "Privacy Settings", you'll get a new list of options, click "Search" then in the drop down menu of "Search Visibility" click on "Only Friends". You may need to check or uncheck some of the boxes below that, depending on what you do or don't want.