I keep 10 each big ones, thorium grenades, and goblin land mines, as well as a fully loaded goblin morter on me at all times, with spares of each in the bank.
The big ones have a phenominal aoe but the stun is really what impressed me, the damage is pretty good too. The cost may seem prohibitive, but putting a big fight on hold for 5 seconds to let your tanks potion up when the healer has run dry on mana can make the difference in preventing a tpw.
The thorium grenades have good damage and a small stun, and are pretty good at giving your healer a break if he's dealing with too much agro.
I'm not too sure how well the mines work. I have them specifically for use in ZF and rarely have time to pay attention to them.
I also try to keep 3-5 masterwork target dummies on me as well, but I cringe every time I use one. Its almost better to die than pay for the thorium alone on those things.