I really like having the Dock hidden, but I also want to be able to customize it even further than the Finder lets me. I think a transparent Dock looks a lot better. The icons simply look like they are floating over the background. I also like changing the color of the triangle that is under the icons. This free application called Clear Dock is available on MacUpdate and does all this! Once it is installed, the customization can be done in System Preferences under "Application Enhancer".