Beacon is a part of Facebook's advertisements system that sends data from external websites to Facebook, ostensibly for the purpose of allowing targeted advertisements, and allowing users to share their activities with their friends. Beacon was launched on November 6, 2007 with forty-four partner websites. Follow this link for more info.
1. Download and Install the BlockSite plugin for Firefox.
2. After restarting Firefox select ‘Add-ons’ from the Tools menu.
3. Click the ‘Options’ button on the BlockSite extension.
4. Click the ‘Add’ button.
5. Enter http://*facebook.com/beacon/* into the input box. Note the asterisks!
6. Click ‘OK’.
7. Click ‘OK’ again, and you are good to go.
Posted previously at Hack College & the Idea Shower.