I've always wanted make something similar to these ambient lights and fill the walls in my room with RGB LEDs. But, taking it a step further, making all and each one of them controllable. This project will hopefully result on an open-source electronics kit for hobbyists and electronic tinkerers, allowing hardware/software hacking and sensory integration.
If you've always wanted the night club experience for your home, take a crack at Hazard's Instructables.
Here's another interactive LED lighting system hack, this one used in conjunction with a home theater setup that mimics Phillip's Ambilight technology: