Monokai for Gedit is a theme for GtkSourceView based on Monokai Extend for SublimeText.
Monokai in Gedit
You can download it here: https://gist.github.com/LeoIannacone/71028cc3bce04567d77e
Then move the monokai-extend.xml file into your ~/.local/share/gtksourceview-3.0/styles/ and enable it by selecting “Monokai Extended“ in Gedit → Preferences → Font & Colors
Ubuntu Themes with support for GNOME >= 3.12
sudo add-apt-repository ppa:l3on/ubuntu-themes-gnome-shell
sudo apt-get update
sudo apt-get install light-themes
For more info, check out lp:~l3on/ubuntu-themes/gnome-shell-fixes.
The patch was applied to the Ubuntu Themes development branch.
The GNOME environment comes from the gnome3-staging ppa.