DMX - rosco-pc/propeller-wiki GitHub Wiki
DMX512-A is an RS-485 based communications protocol that is most commonly used to control stage lighting and effects. Wikipedia has lots of background information. And there is a web site dedicated to DMX, and another that has the full standard
Drivers
On the Object exchange there is a DMX-512A Receive Driver created by Timothy D. Swieter
Jon Williams' November, '09 Spin Zone column (#3) discusses DMX. You can download it from Parallax.
There is also a thread containing a DMX transmitter by Teva McMillan
Projects
Timothy D. Swieter created a DMX controlled light show built into his bookshelves and there's a nice video of it on YouTube.