There's always the classic "Flying Bat". Take a small piece of gaffer's tape and place it near the top of the head close to the hoop. Only a small amount of the tape touches the head and it does a bit of muffling. A bigger bat does more muffling of course. I agree with the comment about paying attention to what your drums sound like out front. Often it's far different from how they sound behind the kit.
I’ve tried everything: moon gel, rings, tape, towels, on G1 clear heads, and I always go back to moon gel. It’s easy to use and I can manipulate the sound with positioning and quantity. It’s so much better than tape, IMO.
And to those who don’t like the “wide open” sound of un-muffled toms, maybe it’s cuz the music you listen to has loud, short thuds. Pretty common in dense-sounding music.