Hot Bike mentioned the Zippo Hand Warmer as a necessity when camping out while the weather starts to cool off:
So that evening ride has gotten your paws chilled, and it’s next to impossible to put your tent up? Well, check out this handy little hand warmer. This pocketable mini furnace makes heat by a lighter-fluid-powered catalytic burner. Once the unit is lit it is slid into a handy Zippo warming bag, and hours of warmth can be expected.
MSRP: $19.95 // zippo.com