Relying on your cell phone to keep in touch with your business and customers means having to ensure it functions no matter how long you're on the road. There are several ways to keep your phone juiced up even if you have long stretches between access to a power outlet.
Some entrepreneurs keep a spare battery or extended battery around, but that's not your only option. American Power Conversion offers a USB Cell Phone Charger that lets you recharge your phone through any running computer with a USB port. That's a convenient option for travelers with laptops and also eliminates the need to carry around a bulky recharger. Pricing starts at $15.
Compact Power Systems makes a product called Cellboost, a disposable battery/charger for cell phones. The device weighs just over an ounce and provides up to 60 minutes of talk time or 60 hours of standby time. That positions it as an emergency option in case your battery unexpectedly dies. Each Cellboost costs about $10--cheap enough to stash several in your car, briefcase or desk.