Anyone who has tried to get a community site working (as I have with ICTA-AU and missiontech.info) will undertsand the 90-9-1 rule
- 90% are lurkers
- 9% contribute occasionally, and
- 1% account for most of the contributions.
Jakob Nielsen, the usability expert, has written on this phenomon toay.
Very interesting. He has some ideas on how to address it, but it does seem that all you can do is skew things to include more people, rather than getting all to contribute.