Iminta has a cool thing going for it: you can put your followers in groups and specify which group sees what... I really like the idea of variable resolution for social feeds. Still in beta as of 3/16/08
Socialthing! is in private beta - see everything that's going on with your friends in all the sites you use, easily figure out where you're missing connections with your friends, interact with multiple sites at once, and more!
I think that there are still other opportunities for marketing companies to leverage Social Media. It isn't just to use social media as a feedback tool - that is but one of the many marketing objectives that may cause a company to engage in a social media