Ever have the nightmare of running out of propane gas with a deck full of guests? This little gadget can save the party. The GasWatch propane-level indicator screws onto the connection between the propane tank and the grill’s regulator and works like a car’s gas gauge. When the dial hits red, you have about 15 minutes of propane left. It can also detect leaks in the gas connection. The device costs $20 at Ace Hardware and True Value stores. An electronic model that sounds an alarm when you enter the yellow zone is $30.