If you want to paint them black get the high-heat black that's used
for barbeques and engines. I believe those are intended not to give
off toxic fumes while you cook?
See below for example:
http://www.rustoleum.com/Product.asp?frm_product_id=39&SBL=1
I don't know about painting them, but I bought a set of black drip pans to
replace the chrome ones. I didn't like them - the chrome ones reflect the
heat radiated downward by the heating element back up towards the pot or
pan, where it has a chance to do some good. The black ones absorbed the
heat and conducted it to the stovetop - the whole top got warm.
The only good thing I can say about the black ones is that they looked
better - unlike the shiny chrome ones, they don't show every drip and
spatter.