TopTaggers - join
Del.icio.us users who bookmark helpful/timely links with meaningful tags (as evidenced by others subsequently doing the same) are rewarded with free advertising, influence on search rankings, and recognition as experts.
Low activity, 104 members, moderated

BlinkList - join
This is a discussion forum where you can exchange information and share ideas with other users of Blinklist - a website organization, bookmarking and colloboration tool from MindValley Labs. www.BlinkList.com.
Low activity, 867 members

google.public.labs.personalized - join
Low activity, 171 subscribers, Usenet