Over on the IVC Wiki, there is a nice writeup on how to create a giant bandwidth meter using a couple Arduinos, an ethernet shield, and some long sections of RGB LED strips.
After discovering how cool RGB LED strips are, I decided to make a bandwidth monitor for the Internet connection at our place. Since there are many users active on the same connection there’s bound to be conflicts where someone is gaming and another is downloading, causing the ping to fluctuate (even with QoS HTB-init set up).
These LED strips are fun and glowy. There are 32 RGB LEDs per meter, and you can control each LED individually! Yes, that’s right, this is the digitally-addressable type of LED strip. You can set the color of each LED’s red, green and blue component with 7-bit PWM precision (so 21-bit color per pixel). The LEDs are controlled by shift-registers that are chained up down the strip so you can shorten or lengthen the strip. Only 2 digital output pins are required to send data down. The PWM is built into each chip so once you set the color you can stop talking to the strip and it will continue to PWM all the LEDs for you.