We have been working in social space for a while now - enhancing our clients marketing with online p2p communications; for an insight into social markets I offer the following.

Not all social channels work the same as others; not all work the same for everyone.

try and look at social channels as sub-channels; when you audit the results, you will see which sub-channels in this space work best for you.

here are 4 main sub-channels in the social space that I will identify for this post - there are more, so your ideas are very welcome.

Active Discussions - discussions that make people act on an initiative, like a contest:
Frugalshopper.ca
Contestcanadda
PlentyofFish

Passive Discussions - discussion forums where people just go to chat with like minded people:
aintitcool.com
fan sites
tranceaddict.com
torontojungle.com

One Post - post something once, people respond:
Ebay
Craigslist
Wikipedia
Kijiji
YouTube 

Social Networks - we all know what these are:
Facebook
Flickr
Myspace
Linkdin

Sometimes one type of social sub-channel can house various other sub-channels, (namely social networks). however, the audiences who interact in these places still fall under the same type of breakdown, depending on their activity within the network.

There are many, many more social networks and word of mouth channels opening online - where will it all net out in the end? That is hard to say, but as it takes shape we will be there, segmenting and tracking its development. The sub-channels above are only the beginning.