From your browser history to your bookmarks!
When you click on the open book that is at the left of the bookmark bar in Safari, you get the whole list of bookmarks. There is also a section in there for the History. I never really realized it was there and I only used the History menu. It can be useful for something completely different though. If there is a URL in your history that you would like to bookmark, instead of loading the website and going to "Bookmark this site", you can simply find it in this History section and drag it right over to the Bookmarks. It is that simple and it will even work offline.