I was reading over at techdrivein.com and discovered this amazing thread. The top  7 Brilliant GNOME GTK Themes. Which i must say if i run ubuntu or mint with GTK, i would use these in a heart beat. Really amazing themes. So check it out on there site or view below!

Divergence IV - A New Hope GTK Theme

Illi! 0.5 GNOME GTK Theme
Equinox+Faenza theme ubuntu
Elegant Gnome Theme Pack Ubuntu PPA
Orta GNOME GTK Theme
Absolute GNOME GTK Theme
Victory GNOME GTK Theme