I've always been a fan of the Ambiance theme from Ubuntu 10.04. After I upgraded linux mint 14 to 16 (in a hacked together fasion using the sources.list from mint 16), the hacked-together theme I had made based on Ambiance from 12.04 was no longer working. In the end, I made a theme that looked better than the 12.04 theme ever did, based on the 10.04 theme. It even has some degree of GTK 3 support, made by me just copying the GTK-3.0 stuff straight out of the 12.04 theme. The GTK4 apps look slightly different, but still look superior to the default gnome 3 theme in my opinion. The GTK 2 theme may not work in Cinnamon, but will definitely work in MATE. Porting parts of this to GTK 3 shouldn't be too difficult if you use the 12.04 Ambiance theme (which is GTK3 compatible) as a base. Right now, GTK3 support is very limited, just good enough to not be considered bad. But as I use MATE and most applications still use GTK2 anyway, this works for now!
My current desktop:
Click image to see full version.
In this picture, I am using the Tahoma font for everything but monospaced fonts (where i use a bitmap version of courier) and Nestopia is a GTK3 app; OpenMSX is a GTK 2 app.
To install it, download this
https://dl.dropboxusercontent.com/u/745 ... .04.tar.xz
move it into /usr/share/themes
sudo mv Ambiance10.04.tar.xz /usr/share/themes
and extract it.
sudo tar Jxvf Ambiance10.04.tar.xz
and then, delete the archive.
sudo rm Ambiance10.04.tar.xz