I know quite a few people use Foxmarks to synchronize and backup their Firefox bookmarks. Lenny let me know that Foxmarks has a mobile website that allows you to access your bookmarks from your BlackBerry. I have started using it as my new homepage and it works quite well. Nothing crazy or revolutionary but it is definitely useful.
If you already have a Foxmarks account you can just view the mobile version at my.foxmarks.com/mobile
If you do not have an account you can pickup the plugin and register at www.foxmarks.com