Okay, my very generic, and more forum management than style tips:
Get a custom style on the forum, as apart from a logo, it is the exact vBulletin default, which does not look professional. This includes status icons, post icons, smilies, actually, probably forget the smily bit, but the smilies are not showing up in FireFox, only text.
Try and get a bit more member activity, as 4000- posts for 67 members is not exactly a great number and many people despise inactive forums.
Try and make the logo blend into the background somewhat, as there is a white border round in FireFox.
Try and fill up many of the 1-2 post forums, as that makes the forum look dead.