I've got the same things on my kit. 4, 6, and 8 inch.
Personally, I put remo
pinstripes on them, to really deaden the ping sound, then I tuned them up real high. I use them for effects sounds, like when playing Tool songs, or as a substitute for cowbells, but alas, they usually stay home from gigs as there is little need for them in my punk band.
I have seen guys in death metal bands using them before, usually set up to the left above the hats as a continuation of their toms.
Anyway, talk to your music shop guys about what heads to chuck on them and just mess around, you might be surprised what you come up with.