Apparently, the only thing that stopped developers from creating useful OpenOffice.org extensions was the lack of a place to publish them. With the launch of the OpenOffice.org Extension Repository, the number of extensions listed there has shot up, and there are no signs of a slowdown. Although quantity doesn't always mean quality, the repository already offers a few nifty extensions that can expand the functionality of OpenOffice.org and make your work more efficient.
On the face of it, the Bookmarks Menu just adds bookmarks to documents, but dig deeper and you'll discover that this extension can do much more. Once you've installed the Bookmarks Menu, it appears only in the Tools -> Add-Ons menu.