ColorDock provides numerous, highly customizable, options to change the look and feel of your dock. It allows you to modify the opacity and background color of the dock, along with options to add a border or change the icon limit to a desirable value. However the highlight of this tweak is it's dock image tinting process. What separates it from other tweaks/themes is the fact that it dynamically applies a tint to the dock image, instead of relying on image substitution (which leads to incompatibility with orientation changes, and yields poor images). For the colorful :P
Configure options from Settings.
See larger Screenshots below..