“Finestly” is the most recent proposed theme for inclusion in Ubuntu 10.04 Lucid Lynx.
A heavily dark theme that works well with the Humanity Dark icon set, it is sure to be popular amongst many users. Google Chrome/Chromium adapts flawlessly to it, system menus look incredibly slick and the metacity is utterly gorgeous.
Will it make it into Lucid? Who knows, but for now you can download it and try it out!
Edit: there is now a light version of this theme, see: www.omgubuntu.co.uk/finestly-lucid-theme-gets-white-edition