Hi,
We recently developed a keyword completion / search suggestion plugin for VBulletin.

Description:
Keyword Complete for VBulletin (or VBKC, VBulletin Keyword Complete) is an add-on feature to VBulletin forums that will add keyword completion features to its search function. Keyword completion, auto suggestion or term suggestion aims to assist forum users in searching for content by suggesting accurate search terms to the user, similar to what Google has implemented on its search engine.
VBKC will integrate instantly into your VBulletin forum, and full customization and configuration is done purely from the admin panel. Free installation services will be provided, as well as a full 30 day money back guarantee. To learn more, visit soft51.com
Do check out and if it's a feature you want, please contact me about it.