We tried sharing a niche interest blog post on three social networking sites: Delicious, Facebook and Twitter. All we did was post the same commentary and the link on our Delicious bookmarks, publish it via RSS on a Facebook profile (and in the status update)and write a short Tweet.
The size of each network was broadly comparable:
The Facebook profile had 169 friends - slightly above average
The Delicious profile is used twice a day
The Twitter account had 106 followers - slightly less than average
The Delicious post didn't result in any traffic
The Facebook update resulted in a ratio of 10% click throughs to friends
Twitter resulted in 30% click through to friends and was RT once and 30 of these were from the key audience.
Moreover, on searching Twitter, we discovered that 4 older links had also been shared
So Twitter is really valuable for sharing links to generate traffic in realtime. We speculate that this is because:
The network is smaller and the information more valuable
The posts are pushed out to you rather than pulled in from Facebook
The links are most trustworthy