Handheld electronics and low temperatures are lousy bedfellows, and your iPhone is no exception. Face it: if you've got a long, cold day of riding ahead of you, you're looking at 2-3 hours of battery life tops -- and that's if your phone is stashed away under layers of clothing, where a trickle of body heat will keep it from freezing outright. Throw that poor thing a cold-weather lifeline with the Mophie Juice Pack Plus Outdoor Edition.

WHAT IT IS:
Made for all iPhone 4 models, the Mophie Juice Pack Plus Outdoor Edition is an iPhone case with a rechargeable iPhone battery built right in. Did you catch that? It protects your phone and charges it at the same time. The shockproof, dual-injected shell is practically bulletproof, yet the case is slim and ergonomic -- this is no pocket-brick. Hidden underneath is the slim rechargeable battery, which remains in standby mode until you need a charge. Flip the switch and voilà, you're back in business.

WHY IT RULES:
An iPhone case with a built-in charger that doubles your battery life? It's the kind of idea you wish you'd thought of yourself. Like a superhero, your Juice Pack conceals its secret powers until they're needed, then swoops in for the rescue. Mophie has also created a free "Outdoor Edition" app that you can download to map your progress, speed, distance and elevation, which is icing on the cake in this instance.

WHERE TO FIND IT:
Head to Mophie.com to order the Juice Pack Plus Outdoor Edition online, or to find a nearby consumer electronics store that might carry it.