I ordered my Pi and tons of accessories (including some relays) a few days ago. I've been looking for a solid-state way to use my Pi as a light dimmer (without using a motor).
The only thing I was able to come up with, is having a solid state relay switch on and off really fast to dim the lights, but I'm not sure that will work (for example, 120hz = 50% power). I'm not experienced in this stuff, but even by my logic, that doesn't seem ideal. Unfortunately, I haven't been able to find a better way to do it.