ClearDock – Change the Dock’s background
By default, the Mac OS X Dock has a semitransparent white background that holsters the Dock’s icons. ClearDock is a nice little utility that allows you to customize the Dock background to be completely transparent, or if you’d prefer, you can select a different semitransparent color. It’s super easy to use, and best of all, it’s completely free. Check out the screenshot below to see the transparent effect in action.
ClearDock features:
- Remove white Dock background under all Dock icons.
- Change the white Dock background color to any other color.
- Change the applications triangle color.

Nice! A non-hacky, non-costy (sorry) way to change the doc background. Thanks for the info!
Tell me, though: what is that 7th app shown in your doc? It intrigues me because the icon looks very much like a computer I used to work with waaaaaay back in the early 1980s called the NEC APC.
You can also make hidden applications in the dock transparent by following this guide:
http://www.zaphu.com/2007/08/20/advanced-mac-os-x-user-101-customize-the-dock/
Cheers!
Yes but how do you alter the triangle color? mine are staying black.
how to change the docks background??
It didn“t work for me. I think Lion is the problem