Padlet was one of the apps we looked at. The posts to this online "wall" are a good example of how social tasks engaged students and helped to build a community.
Another wall created for this task (
http://padlet.com/apjhorton/classroom) shows the collaborative benefit of the course, as learners shared their experiences and recommended a range of resources and apps, some of which will probably feature among this year's Twelve Apps.
We felt it was important to maintain an element of fun for participants throughout the course. The daily cracker jokes were part of this, as was the light-hearted choice for the final app.