This is a topic that has been getting a lot of discussion at the Online Community Summit in Sonoma today.  Hearing a bunch of ideas, but want to get your opinion as well.

From the online commnity summit crowd:

* a combination of growth over time of traffic, content, and users

* number of new advocate/influencers

* increased loyalty

* amount of traffic

Each community SHOULD have their own algorithm for calculating CHI (Community Health Index) what is yours and what do you call it besides community health index.  I've heard engagement metrics, etc.