Ubuntu's unity-tweak-tool only has three themes, Ambiance, Highcontrast, and Radiance.
The repository appears to have quiet a few. I installed gnome-themes-ubuntu via Synaptic. The description shows it contains, Dust, Dust San and New Wave.
None of those three appears in the unit-tweak-tool menu. However they do appear in the gnome-tweak-tool's menu. When I select them from gnome-tweak-tool, nothing happens.
Is there another step to use these themes in Ubuntu 14.04?
Also, is there some way of getting a list of themes (more than just the default three mentioned above) for Ubuntu 14.04?