Re: For those of you who use Exotica Coals...
it depends on the age of the glasstop - no joke. I've seen them used directly ontop, but now I've heard a horror story about an older stove that a "formed" stick coal shattered when attempting to heat. Some of the newer coals get VERY hot, and since it's such a small area of heat, it may be more than certain tops can handle.
I have myself, to see if it will work, used a cheap Dollar store frying pan (stay away from the teflon coated ones) to heat the coals. It worked with the naturals and QL's, although it took longer to get them up & running. About 6-10 mins, but it worked.
If your worried about the glass top, either purchase a cheap frying pan or the $10 electric coil stove. Either one will last a good bit and the second one is portable to boot.