This is the homepage for the More Bookmarks Toolbar.
Add a second bookmarks toolbar to Firefox, with a separate set of bookmarks.
For example, use it at work for a separate set of bookmarks that only work on the corporate intranet. You can still use the regular bookmarks toolbar for personal sites, and hide and show either or both. (And with Firefox Sync, keep them consistent across my home and work computers.)
The source code is on Github.