Finally found a web based bookmark managing solution that integrates nicely with Firefox (and other browsers): http://www.myqlinks.com. Other extensions for FireFox just didn't feel right and were not so straightforward to use. Also looked at the bookmark manager provided by Yahoo.com but the presentation was just clumsy. myQLinks presents your bookmarks in a much more compact and organized way.
One of the key characteristics of myQLinks is that others can also see you collection, but you do have the possibilty to hide bookmarks for others if you want. In case you're interested, my bookmark collection can be found here.