Warmth – New proposed theme for Ubuntu 10.04 (lucid)
Warmth uses a blend of light and dark colors to draw the eye to the content of applications. The toolbars and menubars are dark, while the body of the application is light. Also, the lower contrast on the toolbars and menubars make the text and buttons feel blended into the theme, not glaring. Instead of a shiny, glassy effect, which gives a connotation of fragility, Warmth uses gradients, making the theme look more solid and smooth. Finally, Warmth tries to use bright colors in moderation, thus achieving a dimmed look, making the theme less obtrusive.
Warmth's colors are (almost) fully customizable using System > Preferences > Appearance. That is, you can customize any color except the background color of the dark parts and the color of the metacity buttons.
The metacity theme that comes bundled with Warmth is a customized version of the popular Homosapien theme.
Warmth supports Ubuntu Netbook Edition as well, and themes the panel buttons to fit in with the theme.
Install warmth in karmic
NOTE: This won't work in Karmic by default -- it needs the new version of the murrine engine.
If you are using Karmic and still want to try this theme, run these commands in the terminal:
git clone http://git.gnome.org/browse/murrine/
./configure --prefix=/usr --enable-animation
sudo make install
Then you can restart your computer, and install this theme.
or try this
sudo add-apt-repository ppa:suraia/ppa
sudo apt-get update
sudo apt-get install gtk2-engines-murrine
Source from here