Even a very small mod can really be an excellent addition for the webmaster of a forum. I can think of a few examples of mods that really help me run the site.
I think when the plugin system is back in vb5, then vbulletin can attract more people to vb5 rather than vb4. People like Ozzy47 and BirdoPrey5 can extend more.
Sometimes helping by just posting a reply (answer) to something someone is looking for is just as helpful as a full-fledged modification to others.
Not many realize that while myself and the other mods/admins are not on here, I still see Ozzy on here and I sneak in often (I never use invisible mode I mean as a guest browsing) and see him replying more so than others so three words come to mind when I see that: