Safari has added a new feature in the Version 5.0 release called “Extensions”. If you have Safari running version 5 (relatively smoothly, as there have been more than a few problems) you might want to take a look at some of the new extensions you can add:
By far one of the most exciting is the Youtube downloader extension that lets you save a local copy of the content you are watching on Youtube. Quite a bit of fun. It’s on that list at the bottom of the page.
note: many people have reported problems with Safari 5 so you may want to wait until version 5.1 is available and sorts out some of the issues.