A great bit of content from Online Community Report focused on the trends of ...well online communities.
I like the following nuggets:
Online communities that work are:
Search communities (looking for? dates,jobs,friends)..Search communities also enjoy powerful network effects: the larger they are, the more valuable they become (a dynamic not always true with standard online communities).
Trading Communities: (swapping..ebay)
Education Communities: Online education. is booming. .. Consumers understand the concept of e-learning.
Scheduled Events Communities: Corporations increasingly are holding gatherings online: conferences, annual meetings, analyst calls, and working meetings.
Subscriber-based Communities: Salon.com .
Community Consulting Firms: Consulting is possibly the most prosaic aspect of the online community world, but it does generate revenue.
E-mail-based Communities: E-mail continues to be the killer app.
Advocacy Communities: Many online communities don't seek to be profitable. They have other goals in mind: advocacy, education, politics. Advocacy communities are growing quickly in sophistication, thanks in part to new, powerful tools designed specifically for their needs.
CRM Communities: Corporations spend billions of dollars annually on Customer Relationship Management (CRM) programs. Sophisticated online efforts are increasingly involving message boards, Q&A areas, and other community applications.
There are some great links on the actual report. The story provides food for thought around the sites people return to again and again. Reading the communities that work tells us a bit about user behavior that should be considered in designing Internet campaigns and tools that provide value to Internet users. (if you replace the concept of "pay" with "offer you detailed information about themselves" you can see the same set of trends breaking in the advocacy and campaign world.