Here is a list of 5 vBulletin modifications which should be present on every vBulletin forum:

vBSEO Google/Yahoo Sitemap Generator: vBSEO Google/Yahoo Sitemap Generator is one of the most important hacks and every vBulletin forum which wants free traffic from search engines, should install ASAP. vBSEO Google/Yahoo Sitemap Generator is quite easy to setup and helps search engine spiders discover your content easily, though you need to tweak it for best results.

NoSpam!: NoSpam has been quite instrumental in stopping spam bots on my travel forum and the occasional spammer I get is the one who created the account manually. This hack is far superior to captcha and/or email verification and one can use their own questions to ensure only the real users can signup.

Report Bad PM: While NoSpam can easily stop spam bots and you can easily spot manual spamming, pm spamming is something which is hard to control, since an administrator does not know which pm is being sent by the user. Using Report Bad PM hack, members can report a spam/abusive pm to the moderation team in the similar way as a thread/post.

Welcome headers: If vBSEO helps bring visitors to your site and NoSpam helps filter out the spam bots, welcome headers help improve signup rate by presenting a message (editable) to guests on why they should join your forum. You can also use it to display messages to users who haven’t posted in the forums in a while.

passiveVid: If a picture can say thousand words, a video can speak millions. This nifty utility enables your members to embed videos from no less than 30 video uploading sites and that too without the need to use any bbcode! A user simply has to post a link to the video, like this http://www.youtube.com/watch?v=tfNWLcWnzs0 and it is automatically embedded by passiveVid!