Most people have heard of moon gels and just recently they've become even more expensive which is a real shame because there pretty useful.
The moon gels consist of a sticky gel pad a bit like those spider toys thay you throw at walls and they crawl down on the sticky feet. The gels retain they're tackyness through out if you take care of em and don't let them get really dusty you can wash em of. And there stick all over you can cut them in half if one whole one is to much dampening. They work almost perfectly on drum heats as well as cymbals and anything else that may rattle or vibrate in you studio. I can tune my snare so low it sounds awful then chuck 2-3 of these on and it dampens the horrible overtone enough that you end with a drum sounding twice it's size in pitch. The stick the underside of toms nicely baring mide they need be new fresh ones or nice and clean drum head included. And they come with a hand case to keep them in. Now they use to be about £3-4 now there going for round £8 which really annoys me as they're a great product but this is far to much I suggest buying in bulk with some mates to keep the prices down.