I found a couple of sites that might be useful to those who run ATV's. Found one of them on anthoer forum. This stuff claims to seal up 1/4" to 1/2" rips and holes.
www.ultraseal.com/ is one of them and the other is: www.rhinotire.com
I'm going to check out the ultraseal tire sealant. They sell in in one gallon jugs and for about $12, they sell the pump and applicator to put it into the tires.
If anyone has tired either of these or others out, please post what you think of the product.
On a side note, the ultraseal is good to use in all tires, from atv's, cars, pickups, heavy equipment and so on. They have a contract with the U.S. Military and Postal Service.