I've actually come up with a simple solutions for helmet, gloves and especially shoes. I keep a small spray bottle and fill it with rubbing alcohol (the really cheap stuff). After each ride, everything gets a good spray - the alcohol keeps bacteria from forming and causing oder.

I do occasionally wash my helmets in the sink just to get the salt off the straps etc. Also after a mountain bike ride through water, I will soak my shoes in alittle water and bleach. I wear leather Sidi's and they do just fine after drying out in the sun.