The best help would be PHPBB forum or looking at the directory of PHPBB mods to find what you want. You can also look at some of the html source of VBulletin for the AJAX functionality in the posting, if there isn't already a mod of phpBB for this.
Do you mean just adding features to it? Most of vBulletin's features can be added to phpBB via mods. Check the official phpbb.com website and also check Patrick's site phpbbhacks.com - If you have some loose change hanging around, you could hire a developer to create unique features for you, as well.
You should check out PHPBB3 (beta), its far better than vBulletin. There latest complete version is 2.0.21. With list of mods available and little bit of cut and paste of codes you can build a forum far superior than vBulletin. You may like to check following links: