Elegant Brit with some fixes for Gnome 3.4. This is different to the Elegant Blackle theme as I edited the existing theme as opposed to starting from scratch. However, credit where it is due, I did use some css from Elegant Blackle to fix the Brit. A team effort I like to think of it. I've spent a bit of time tidying up the bouncing buttons as well.
Old Elegant Brit Gnome3 with a bunch of other really useful links [link]
Elegant Blackle [link]
Original Elegant Brit Theme [link]
edit: 09/08/12 Stole more css from Blackles infinitely superior scroll bars
edit: 11/08/12 Window resize grabbers are impossible to theme in gtk3. Well done for hardcoding that rubbish corner graphic chaps. So I did it badly.
edit: 1/9/12 Added the gimp ruler fix as suggested in the comments
edit: 13/9/12 Added sanitized .css files supplied by fopref and removed gtk-2.0-testing folder. There is still some minor button bouncing that I can't quite suss out. It's something to do with disabled buttons becoming enabled and then highlighted.