The Active Forum block (http://docs.moodle.org/en/blocks/active_forums) is an easily installed mod for Moodle which pulls titles from the discussion forums and creates a tag cloud for quick reference and to see at a glance what discussions are happening in the online classroom. Just unzip the block in on your server, run Notifications and the tool is available for all teachers to add. The Active Forum block was recently added to the Moodle.org Plugin repository and is supported/created by SiauMeng Nyam for Moodle 1.9 and earlier.
While somewhat similar in function to “Recent Activity” this block takes a different approach to displaying the relevant information. For example, instead of just a digest of what’s going on in the course, the more replies a discussion topic received, the larger it’s title will be in the tag cloud. Pretty slick.
Editing and customizing what is displayed on the block is easily achieved, this is a screenshot of the various configurations (which help control the number of posts, over what time period and whether or not the new forum was included, among others),
For more information or to download the block/read the documentation visit http://moodle.org/mod/data/view.php?d=13&rid=4242.