The Equinox GTK themes is a pack of (now) 5 beautiful themes created by Tiheum (who's also the Faenza icons author).

An update to the Equinox PPA brings 3 new great looking themes: Equinox Evolution Dawn, Dusk and Midnight (which complete the Equinox Evolution series along with the regular Equinox Evolution and Equinox Evolution Light) as well as an updated Equinox GTK engine.