Dark GTK theme for Ubuntu 14.04

NoobsLab has made available through their PPA a new theme entitled Ambience-Dark-Red. It retains the default Unity decorations and icons and simply tweaks colours. Although not as good, it is at this stage the closest to DarkNight you can get for Ubuntu 14.04.

To install Ambience-Dark-Red:

sudo add-apt-repository ppa:noobslab/themes
sudo apt-get update
sudo apt-get install ambiance-dark-red

The original Ambience-Dark theme is also available from NoobsLab. It is a low contrast theme that may be hard to read without the appropriate lighting/brightness.

It can be install with the following terminal commands:

sudo add-apt-repository ppa:noobslab/themes
sudo apt-get update
sudo apt-get install ambiance-dark

An alternative, also from NoobsLab is the GnomishDark theme:

Note that it was a bit buggy on Ubuntu 13.10. To install:

sudo add-apt-repository ppa:noobslab/themes
sudo apt-get update
sudo apt-get install gnomishdark

Update

A few more styles have been made available by NoobsLab:

The Mediterranean package includes some nice blueish themes worth trying. They also impose great changes to window decorations and icons that may not be to everyone's taste.

To install the Meditarranean package:

sudo add-apt-repository ppa:noobslab/themes
sudo apt-get update
sudo apt-get install mediterranean-theme

Numix Bluish is a variation of the Numix theme, with what to my eyes seem violet and green hues. There is again a good deal of customisation regarding icons and window decorations.

To install Numix Bluish:

sudo add-apt-repository ppa:noobslab/themes
sudo apt-get update
sudo apt-get install numix-bluish-theme