URLwell is a simple and unobtrusive menu extra that lets you drag and drop URLs onto its icon to store temporary bookmarks. Once you've visited a bookmark, it's automatically removed from the list.
It's great for those times when you come across a web page that looks like something you might want to take a look at, but you don't have time to do so at that given moment. It's easier and less cluttered than storing such short term bookmarks with your regular bookmarks.