Ever thought about what the most popular plug-ins for Moodle are? Well you can get a peek by looking at the Moodle download stats page (http://download.moodle.org/stats.php) where the plug-ins are listed in descending order, listing the most downloaded at the top*.
Here are the top 5:
The Moodle stats page has a lot of great information (including the download stats for Moodle versions: 1.9 is the most downloaded version with nearly 4600 downloads daily).
Check it out at: http://download.moodle.org/stats.php
*These stats are for the last 60 days period