F.B. Purity is a browser extension / addon that lets you clean up and customise Facebook. It filters out the junk you don't want to see, leaving behind the messages and page elements you do wish to see. The list of message types that FBP hides is customisable to your taste.
Google is collecting a lot of data about how we use the web. The new Google Alarm Firefox addon visually & audibly alerts you whenever your personal information is being sent to Google servers.