For Your Information
Jelsoft's vBulletin
http://www.vbulletin.com
The place for discussion about 'how tos' on settings, installation, etc. The 'official' site.
vBulletin.org
http://www.vbulletin.org
The place to find all
hacks, which modify the way vBulletin works by modifying the actual files themselves. Generally any totally new features are hacks.
vBulletin Templates
http://www.vbulletintemplates.com
This place, for all template modifications which only require editting template (hence the name...), or in some cases BBCode changes or replacements. Usually less complicated changes involved than with the hacks.