Nice article outlining "Five Essential Safari Extensions".
Five Essential Safari Extensions
Web browsers like Firefox, Chrome, and even Internet Explorer have offered support for add-ons and extras since soon after their respective releases. Apple's own Safari browser, however, took seven and a half years to gain support for extensions, which arrived with the recently released Safari 5.
Apple launched its own directory of Safari extensions last month; before then, Jonas Wisser's Safari Extensions blog was the easiest place to find new extensions - but both sites can feel a bit overwhelming. There are hundreds of Safari Extensions, with more arriving every day, so it can be hard to find the signal in the noise. I've already dug up several extensions that vastly improve my own daily Internet-surfing - perhaps they can help you, too.