The about page for memigo talks about customized, news, peer communities, and implicit/explicit rating. MovableBLOG seems to think memigo uses RSS to watch what you link to and TrackBack to ship stuff back into your weblog. Of course I could just follow the link to where memigo documents this interaction, but that would be too easy. Interesting idea, although once again, linking is the only gesture that can be observed by the service.
Guess I should sign up and see what it's all about.