A while ago I posted a thread about making a set of PC fan controllers and LED controllers that would connect with a digital interface (the "fan bus") for computer control. This came from my original project RGB Fan Controller which was a fan controller with 4 color changing LED lights.
I finally figured out an easy way to connect multiple devices to one serial port and made a minimized version of my original PCB that should be able to attach directly on the side of a 120mm fan. I plan on printing and building the boards this weekend and then installing them in my Antec 900 case (changing the two front fans and the side fan). The fans I plan to modify are Rosewill white LED fans, one has a burned out LED (LED's were pretty cheap quality anyways but the fans are nice).
I also wrote a Processing script that flashes the LED's to music, it works with my original fan controller which is mounted on the side panel:
Once it's done I'll post a video and the board/code files.