Ubuntu 12.04 LTS (Precise Pangolin) uses Unity as the default desktop, developed on the top Gnome 3. So if you’re using Unity or Gnome Shell interface with Ubuntu 12.04, you can try these cool GTK 3 themes – to have more fun in desktop experience with Ubuntu or any other GNU/Linux distributions that uses Gnome 3 (e.g Linux Mint, Fedora etc).
Most of these themes are based on the users ratings and popularity (no_of_downloads) at gnome-look.org or deviantART, download link (to theme page) is there – below each theme.
#3. Gray Day
#4. Adwaita Cupertino
#5. Elegant Brit
#7. OMG Suite
#10. A new Start
Thanks to the theme developers for their awesome themes and screenshots.