Well, listing just 3 is rather difficult, since there are a few others who all deserve first place by me.
All these I nominate for the same reason, because they’re simply beautiful, and are/will be a real inspiration for my current/upcoming forum layout and design.
http://www.atcards.com
http://www.communityofsweden.com
http://www.digart.pl
I’m afraid just one of them is, or was actually build around vBulletin.
Some of the others I do have to list if that’s ok
http://www.talkfreelance.com
http://www.ayyas.com
http://www.e-steki.gr
http://www.vbtech.net
Not really sure if it matters, but most of them really spend some time on their
forumhome,
memberprofile page, and
complete and renewed set of icons (ie. the /misc folder is often forgotten when creating a new style)