Pimp.my.Gmail series!
If you prefer a script, check out : http://userscripts.org/scripts/show/75047

First things first, this style is inspired & built upon the Gmail: tango! icon theme style by smaug@userstyles

This style will Pimp up the Gmail sidebar menu.
The icons in this style are all 22px and taken from various tango icon packages.
So credits to the authors of those packages.

Find the rest of the Pimp.my.Gmail series @ "kilroy_@userstyles"
Also check out some of other Gmail scripts @ http://userscripts.org/scripts

CHANGELOG:
v0.5 : 18-08-2010
- Updated to be compatible with new layout.
- Changed chat icon.
v0.4 : 08-05-2010
- Changed alignment of more menu. Sticks out a bit now.
- Replaced ugly drop-down icon for more menu.
v0.3 : 23-04-2010
- Added icon for the 'more' menu.
- Nice glass effect for labels.
- Some more minor changes.
v0.2 : 08-04-2010
- Optimized the code a bit.
- New screen to show contacts & tasks.
v0.1 : 20-03-2010
- Initial release.