There are also grenades which really are a grenade-shaped styrofoam with a firecracker inside. Its surface is covered by BBs. You light it, throw it... and you can imagine the rest.
I know some companies are developing an airsoft claymore as well.
back when we were stupid kids, shooting each other with BB guns, we had simular gear.
we'd cover large firecrackers with about 3/4" of wax for granades. we'd use a hot knife to carve them into a pineapple shape. when they hit they left a fairly dark bruise.
we had 'claymores' made that fired electricly. they could be set up to be triggered manually, by tripwire, or a compression trigger that you could set upto 10' from the charge. the 'claymore' fired a couple ounces of blue 'chalk-line' chalk, to mark anyone who it 'killed'.
it always frustrated the hell out of our moms, that we wouldn't put that much creativity into something even remotely usefull.
by the time we decided we should stop this screwing around someone really did 'loose an eye' ( he still has the eye but also a BB permanently lodged against his optic nerve, shutting off half of his field of view for one eye). it was fairly difficult coming up with a logical explaination for the sheriff when he investigated this 'gunshot wound' (the hospital had to report it as if it was a real shooting), the best answer I could come up with was that "It seemed to be the thing too do, at the time"