If you've ever used a camera (so, everyone), you know water and dust are a camera's mortal enemy.  At the least, it leads to smudged, out-of-focus photos or it could be the death of your gear (water plus electronics hardly ever ends well). BRNO has come up with the dri+Cap which helps prevent both dust and water from destroying your camera.

You can get either a lens cap or body cap that has a silica pack inside to help regulate humidity.  They've even got a rubberized seal, unlike most standard lens caps, to make sure nothing gets under the cap when you're least suspecting it.  The cap also promises to keep an "ideal" humidity level of 35-45% to make sure no fungus grows.

The silica gel packs (much like the ones you find in new shoes) will need to be replaced, but they're under a dollar each and let you know when to change them -- the packets change color from orange to green.

dri+Caps start at $45 for lenses and the body cap sets are for Nikon and Canon cameras.