The Ozone theme gets revamped for the next release of Lubuntu Oneiric Ocelot. Combining both GTK2 and GTK3 is an added difficulty trying to make the whole environment unified. For that purpose, new GTK apps will use the Unico engine (included in forwarding Ubuntu repositories; download here for testing on Natty).
Download usual resolutions (4:3 and 16:9 fit) in a 2.7 mb archive.
Ozone (version 2) is based on ZukiTwo by Lassekongo (under GPL license). Using Pixmap / Murrine engine (gtk2) and Unico (gtk3). Download the whole theme for both window and controls (52 kb). Remember, it's in alpha stage.
Elementary Monochrome Dark, by Dan Rabbit (with a few modifications).