I previously covered OutFoxed here.
Lijit is currently closing an initial angel round in order to develop the social web tools that were the basis of Stan’s master’s thesis.
I was invited into the beta a while back, and have played with the Firefox plug in since then in my daily use. There are some facets of Lijit that I really like, such as being able to easily see web pages on particular topics that are recommended by my social network. The aspect of this that I like best is that it’s just “there”, you don’t have to go and do anything other than what you normally do (e.g. search google).
If you’d like to get on the list for the beta, visit this page.