1. Reputation management
2. Collborative filtering
3. Mailing list management
4. Content management systems
5. Distributed categorization and indexing efforts

These tools are all related in some way to the process of establishing, developing and maintaining online communities.

Most online community sites are doing some of these things, but no one's gone ahead and incorporated everything. Is it possible? Is it desireable? What features really make for the best, most useful online community environment? How much does the purpose of the community affect the tools that are needed?
...from Online Community Concepts and Technologies at CamWorld