One neat thing that Opera does well is having two viewing panes for the bookmarks. I don’t know if it is better or worse than doing things the normal way – but it is a different way of browsing through things. If you have wanted to do this yourself – but didn’t want to move away from Firefox, have no fear!
All you need to do is pick up the 2 Pane Bookmark extension for Firefox. This extension does it’s best job to bring this functionality from Opera to your browser of choice, Firefox.