No special products needed. Just use the same deodorant/anti-perspirant used under your arms and use it down under. I've been doing it for years and it works great. One swipe under the balls and one in each of your "leg pits" (creases where your leg meets your pubic area).

Honestly, with the public being more open to discussion of this type stuff, I can't believe the deodorant makers haven't started new marketing campaigns. I can just hear it now, "The new product for todays athletic man! "Ball Fresh". Get it today at participating dealers."