vB.Sponsors 1.0.x is an extension for vBulletin 3.5.x that allows you to specify a sponsor for a forum or category.

Features:
Enable sponsorship on forums and categories
Use a banner or a text link
Supports large banners for the top of the sponsored forum and small banners for the forum listing
Tracks hits for each sponsor
Statistics viewable inside Admin CP
Easy to use and install

Version History:
1.1.0 - Code Cleanup/Bugfix/Feature Added
Big banner display now works
Added the ability to change the Forum Sponsored By text
Updated example template code
Cleaned up code (XML, vBSponsors.php, link.php)
Code now more closely matches the vBulletin 3.6.x version (here)
Updated the documentation
1.0.5 - Feature Added/Bug Fix/Code Cleanup
Added a large banner option for the forum that's sponsored by the sponsor
Added FORUMDISPLAY template code
Cleaned up code
-link.php
-vBSponsors.php
Fixed apostrophe bug (apostrophe in sponsor's name caused a SQL error)
1.0.4 - Bug Fix
Corrected statistics database error.
Updated template code
1.0.3 - Bug Fix
Corrected settings bug (settings not being saved)
Fixed parser error.
1.0.2 - Features Added
Added Admin CP block
Stats are now viewable in the Admin CP by administrators
Minor template changes (please verify your code if upgrading)
1.0.1 - Bug Fix
Corrected issue with vBSponsors table. Now correctly adds statstics.
1.0.0 - Initial Release

This extension stands above others in that it will also track hits to a given sponsor. You can view the statistics from within the Admin CP in vBulletin.

Download:
You can read more and download it from vBulletin.org here.

Documentation:
Documentation is hosted on this site.  View it here.

Donate:
You can help with the development costs (server, software, etc.) by sending a donation. It's not required though.