Restyle the web with Stylish, a user styles manager. Stylish lets you easily install themes and skins for Google, Facebook, YouTube, Orkut, and many, many other sites. You can even customize Firefox and other programs themselves.
Official eBay add-on. Keep an eye on your eBay activity wherever you are on the web when you install the eBay Sidebar for Firefox. It’s a free tool built with eBay users in mind that will help you get more out of your buying and selling on eBay.