I agree with the stuff about not using the handbrake (I once killed the calipers on my old Citroen AX by leaving it with the handbrake on for a few months - doh!)

But also remeber that the pads float very close to the discs all the time so even with the handbrake off if you leave it for a long time rust can build up and stick to the pads (and at the least you will experience a light grinding noise when you first run it again which is the rust being worn off the discs). One solution (not very practical I know) is never to leave it idle for a long time if you have just driven it it wet weather. Porsche Boxsters have a real issue with this and lots of people have been stung for new discs or skimming after wrecking them; it doesn't sound like the NSX is anything like as bad in this respect.

(The real solution is to use your NSX everyday! Cars need driving!)