btopro
commented
11 years ago https://drupal.psu.edu/content/modules-context-collaborative-learning-environment -- skip to the 12 minute mark in the video. I talk about an implementation of Radioactivity i'm using in the collaborative learning environment distribution.
Pros: Awesome concept, exportable, easy to setup and very powerful when you put a little effort into planning out how to implement.
Cons: Uses its own php file to "radiate" which can be concerning on some level. potentially very intense processing wise
ultimately id recommend it, just make sure theres enough conversation up front about it
http://drupal.org/project/radioactivity