One of the most useful gadgets you can take along on your car trip is the one that lets you power up all the other gadgets. An inverter changes the 12-volt direct current from your car's battery into the 115-volt alternating current used by most appliances. You can operate a small television, a laptop computer, a toaster or a coffee maker with that.
Inverters come in a variety of sizes. Smaller ones, like the Kensington K38037US, fit into the glove box and plug into the lighter/power outlet. In addition to giving you AC power, it lets you charge your smart phone or iPod through a USB cable. Larger inverters can be wired directly to the battery. A model from Power Line looks exactly like a coffee cup. Plug it in and you have two AC outlets in your cup holder.
Keep in mind that the power in your battery is limited. You'll have to look at the maximum load of any inverter you use. You may need to turn on and run your engine periodically to make sure you're not draining your battery.