The PimpStar.

From the website:

The PimpStar is a huge leap forward in the evolution of the wheel. With the PimpStar’s built-in full color LED lights, microprocessor and wireless modem, you can display virtually any image, including text, graphics, logos, and even digital photos!

The included software allows you to create your own images and send them to each wheel individually or all wheels at the same time as you drive! You can even pre-load up to six images into each wheel and program them to change automatically at the time intervals you select. The wheels are environmentally sealed, so you don’t have to worry about going to the car wash; and they are powered by the vehicle electrical system so there are no batteries to run out or change, ever.

Link (don’t miss the video! via Fastback)