BuddyFox is an instant messaging addon for Firefox browser that allows you to chat chat online and share links without leaving your browser window.
After creating an account on BuddyFox.com you download the addon and install it in Firefox. A small icon will appear in the status bar and clicking it will slide open the chat window with the list of your friends on the side.
Using the icons you can add new friends and even create groups where you can talk to all of them at the same time.
The chat is smooth, even with multiple people at once. You can also simply drag and drop links from the pages you are viewing to your friends.