Extreme Dock Makeover: Leopard Edition
No, Ty Pennington is not going to help you change the way your Dock looks in Leopard, but James Shiner will.
James Shiner is the operator of LeopardDocks, a site that hosts Dock Replacement images, and the Dock Replacement Automator script (by Brian Rice). He has archived 70+ Dock replacement images for your enjoyment, including many colors, patterns, and open application indicators.
Make sure you read the instructions carefully, because when I tried to replace my dock images, it didn’t work initially. You have to delete the old dock image files before you can move the new ones over. Make sure you back up the original files, but in case you don’t, Shiner hosts the original files on the site. After a quick Terminal command to restart the Dock, the image files will load correctly.
The Automator script did not work for me, but your mileage may vary.
In case you don’t like the 3d dock, there are also instructions for making the dock 2d with the new iteration (which can be seen when the dock is set to display on the left or right side of the screen), or the classic iteration.
Hopefully in the future, there will be a better software solution to cosmetically changing the dock (like the popular utility ClearDock, which is not currently compatible with Leopard).
Good luck, and try to avoid Leopard Fashion Faux Pas.

Broken link, the correct address is
whttp://www.leoparddocks.net , not leoparddocks.com.
Hmmm I’m pretty sure it is leoparddocks.com – but the site appears to be down, shortly after this was posted.
The link is not broken. That is an alternative site.
[...] Dica: MacApper [...]