What the world needs right about now is gtk themes that are consistent across gtk2 and gtk3.
This is my adaptation of Ubuntu Lucid's Ambiance theme, which I have been using for about a year and a half now.
It's a light, rather than a dark theme, with an optimistic feel, blue scrollbar handles and wildly clashing red progress bars.

I've made a gtk3 version of it, based on an adaptation of Ambiance for gtk3. I could wish for better gradients in the scrollbar troughs, and would be grateful for any help anyone can afford.

I recommend this theme for use with the Dropline Nou! icon set from Sylvestre Herrera, and with my own blueglass-adamised emerald theme.

I hope this brings some more colour to gnome 3, and a smoother transition as apps graudally get ported from gtk2 to gtk3.

HOWTO: Install the unpacked contents of the archive into /usr/share/themes/Adbiance. Set permissions to 777. Set Adbiance as your theme in gconf-editor (apps-metacity-general-theme, desktop-gnome-interface-theme) and dconf-editor (org-gnome-desktop-interface-gtk-theme), select it in gnome-appearance-properties, and specify it in your .gtk-2.0-kde4 and /root/.gtkrc-2.0 files.

P.S. I'd love to know what you think since this is my first contribution!