I really liked the comment Sarah Blow left below about the way she measures the effectiveness of online communities. "We measure our impact through the reach of our network and through the feedback that we get from our members. The day that we aren't helping or people no longer feel the need for such a network is the day that we will fold up and move on to something else. Another way of looking at impact is to ask people where the value in the community lies. Look at the information, the connections, the ability to create change and so on. There are all powerful things within communities. Also look at the number of members and how many are active participants." Easy, huh? Who needs metrics? Just care!