A highlight from Jeff Jarvis:
“Explosive web companies—Skype, eBay, craigslist, Facebook, Amazon, YouTube, Twitter, Flickr, and Google itself—don’t charge users as much as the market will bear. They charge as little as they can bear. That is how they maximize growth and value for everyone in the network.”
Lets adapt this for communities.
If your business is building a community, ask as little from each member as you can.
Collect as little data as possible, send as few promotional messages as you can (preferably none) and reduce actions that don't add value for members to an absolute minimum. Resist every urge to send selfish-minded e-mails to your more active members.
Ask each member to give the minimum you can afford, and you'll get the maximum from your entire community.