AllBookmarks is a simple, free menubar application from the makers of 1Password. Basically it gives you one-click access to all your Safari, Firefox, OmniWeb, Camino and Flock bookmarks as well as your 1Password Bookmarks (if you have 1Password installed). The interface includes a live search box, though it doesn't seem to work as well as I would like. Nonetheless, it's relatively easy to navigate the hierarchical menus.
AllBookmarks is a free download from Agile Web Solutions.