Five Card Flicker
http://5card.cogdogblog.com//index.php
Alan Levine has some good ideas for story sharing - use random cards/images and ask people to create their own story.
https://twitter.com/Edtech001
Also check out our Twitter account - I have been experimenting for Deirdre who is writing the Introduction to Addictions course for the Learning Design Project. We can add Twitter as a block/widget but I think we'd have to set up a unique Twitter account for the course - it's a way of getting updates and news - for example I followed Alcohol Justice and got various updates (now unfollowed as not general enough). 
I have also been experimenting with Comments as a block - I quite like this - it replicates some of the ideas in Facebook.
Let us know if you want some help/ideas/thoughts or you have other ways. We are still hoping that one day we'll have that app that sends notes to facebook letting groups know that their tutor or colleagues has posted something fabulous in Moodle. Manana. Pero. Apopo, ae?