Hi all,
In a recent meeting, a bunch of us discussed the various design styles specified in skins, jQuery.ui, the newer mediawiki.ui library, and in other places. There was general agreement that we're shooting for consistency as the ideal, but that we've got a lot of work ahead to standardize on any one look and feel, even just for Vector users.
One step agreed on was doing an audit of all the places and ways Vector, jQuery.ui, or mediawiki.ui are applied today. To that end, S Page started http://www.mediawiki.org/wiki/Design_audit and an associated category today.
Normally I try to upload screenshots to Commons, but it's kind of a pain in the butt to upload MediaWiki screenshots there because you have use custom licensing templates every time. So if you just want to upload locally to MediaWiki.org like S was doing I think that works. We also considered just opening a Dropbox folder, since this stuff doesn't necessarily need to be permanent.
Anyway, this is a good place to start. Thanks to S for kicking it off.