Oh, I was going to do a quick explanation of sources (I am about to do this in class :D)
Radio - caused by large oscillation of electric charges - any A.C. running along a wire 10+cm long will give out a bit of radio wave
Microwave - same cause as radio, but shorter wavelength. I always use a microwave oven as a baseline. There's about 2-3 waves fitting into an oven.
IR - Now we get a bit smaller, thermal infrared is caused by oscillation of molecules - anything warm (above absolute zero) will be giving off IR
Visible - (as well as Near-IR) is caused by atomic vibrations or high energy heating (bulbs, THE SUN)
UV - now we start getting into energy transitions in the atom - things getting hit by other EM radiation can cause this and make stuff give off UV. Interestingly, UV paint/ink doesn't "glow" in UV, it absorbs UV light and re-emits in in a lower frequency, otherwise we wouldn't be able to see it.
X-Rays - you can give off x-rays with REALLY hot stuff. In fact, old X-ray sources would be similar to a souped up CRT. Also, pulling sellotape fast off the rolls gives off a few x-rays :)
Gamma - can only be cause by stuff going on in the nucleus - radioactive materials, nuclear bombs, fission, fusion, or nuclei that have been excited someway.
That's fair enough. I guess it's just not for me.
I need two hands to count the number of computers I own and make use of. I use at least 4 of those on a day to day basis.