DC Template Manager offers a convenient way of moving the contents of many templates between the database and the filesystem simultaneously.
This module will let you add documentation specific to your site into the Control Panel, and link to it by creating a new control panel tab.
The Defensio module integrates EE with the Defensio spam filtering service.
The Digital Commerce module allows you to sell items (both downloadable and tangible), without requiring the purchaser to first register as a member of your site.
DynPI is a Dynamic Plugin Interface for EE. Code your plugins from the Control Panel and store them in your database, instead of in files.
Are you looking for a community building solution that integrates seamlessly with your ExpressionEngine installation? You've just found it!