J and D Components are selling plastic sabots to reloaders (along with providing load data). For those of you who don't know, this allows you to do some very interesting ballistic-type things, such as shooting .223 projectiles from 30-06 barrels at Holy Crap! fps velocities. Or turning that .30 Carbine into The Gun Varmits Fear.
The possibilities for entertainment are just...astounding. I want to see one for the .50 BMG, which could be used to put a 55 gr. payload into low earth orbit.