As the batteries in mobile handsets have improved, running out of power seems to have become less of a problem. But as battery-draining features like Wi-Fi and mobile TV proliferate, perhaps it will be a bigger issue. It’s interesting, then, to see companies announcing different products to give mobile users a boost when they’re low on juice.

Motorola this week announced the Portable Power P970, essentially a portable, rechargeable battery that can be used to charge devices with a mini-USB port. This follow Energizer’s announcement of its EnergiToGo product, which uses four AA batteries in a charger to power phones, as well as things like iPods, PSPs and Nintendo DS systems.

A little more interesting idea, though, comes from a company I met at CTIA, Medis Technologies, which has a disposable fuel-cell product that works in much the same way as the other two products. It’s a cool little box, really designed for sort of “emergency” use. It’s a self-contained fuel cell that will cost $20-25, and provide about 20 watt hours of power. It’s safe, “green”, and not combustible, and sounds like it would be pretty ideal to get and stick in your car’s glove box or something in case of emergency. The fuel cell’s not quite ready to displace the battery yet, but Medis says it is working on making its technology smaller and more powerful — the common goal of anybody in the field.