Well, if it's raining when you're out caching, and you want to wait in the car for a while to see if it lets up, I recommend the game Bejeweled!, available from the PalmOne website.

It's addictive, although I wouldn't pay the $20 shareware cost. It's crippleware - the wait for the game to start gets longer each time you play it (an incentive to get you to buy it).