del.icio.us
I just started using del.icio.us as well. While not quite as life changing as Google Search History, this site is pretty cool. I browse to a LOT of sites through the course of my work, and the better ones I want to remember. The bookmarklet feature makes it as convenient as adding a favorite.
del.icio.us is also a great example of a RESTful architecture. More about that later.