For example: say you are following xenforo and you want to display and tweets and any facebook news that xenforo makes, you can do so via this sidebar block.
Here's what the block looks like:
It was created by Developers at SOE but getting a hold of them is like next to impossible. I tried a PM with their admin account and a few e-mails to some of the developers I personally know. They don't even seem to know who the webmaster is. So now 'm requesting it here.
There are live demos of it on their sites here and here.