A great little demo of chemiluminescence taken from the NurdRage website – (If you haven’t been there, you should)
It is based on the simple luminol reaction with copper ions and peroxide. In this case, though, the copper ions are produced in situ by the action of ammonia on copper coins (or pieces of wire). To prevent the solution just ending up a luminous blue, EDTA is added that chelates the free copper ions. The end result is that you get a blue glow around the copper but not elsewhere.
Here’s a link to the NurdRage instructional video. (opens in new window)
And here’s a video I took of it on my phone.