My custom plank theme that's basically a better elementary OS Jupiter dock theme.
- Extract the files and place them into ~/.config/plank/ replacing the existing files (this will overwrite the default theme, so back it up if you care to).
- Plank should immediately reflect the changes. If not, it will after restarting.
Updated Tue Dec 11, 2012: Renamed from "Pantheon" to "Jupiter Redux" since the Pantheon theme is now white. Also removed "Renderer" from the section titles so it won't get overwritten with a Plank update.