Throbber Button enables you to click on the Activity Indicator (throbber), which takes you to the web site of your choice. This site can be configured from the Addons Extension Options screen.
You can now open multiple sites at once by separating each URL with the pipe (|) character. As before, you can specify where you want the site(s) to open: either in background tabs, foreground tabs, or new windows.
Note: A similar feature was present in Firefox 1.5, but no longer exists in Firefox 2.0 and later. Throbber Button brings this feature back.