Take a look at the Screen-shot,


It is a Greasemonkey skin for GMail.
Try it now! Few days back I got this link from my
friend.
It works only on Firefox, download
new black Gmail skin here and the latest version of
Firefox3 here!
After installing, GoTo: Tools --> Better Gmail 2... and play with the options.
PS: No need to install Greasemonkey for this GMail Skin.
Update:GMail is now updated with their own set of themes, read about
GMail Themes here!
To add theme to your GMail account, go to "Settings" and search for "Themes" tab
Labels: GMail, GMail Tips, Themes