I'm a huge fan of this tool. The Atomos Power Station. I've only had it for a few months but I've already used it more times than I can count. I use this thing every day when I'm filming. If I didn't have it with me, I wish I did.
I've been eyeing this product for about a year now... When I got it, I had the fortune to use this thing on a "major set." while we were shooting video with a RED, we were recording sound with my Tascam using the Atomos Power Station for power. It worked like a charm then, and I've loved it ever since.
There's so many things you can power with it. Cameras, mixers, jibs, phones, tablets, monitors, recorders, even some lights... and probably a whole lot more with the addition of adapters... probably some D-tap accessories like wireless follow focuses. I'm already buying 2.1mm cables to use with other things at a distance. My jib's motorized head can use the 2.1mm cord supplied, but then I need to power my monitor with house power and vice-versa, if I had another 2.1mm cord, I could power both from the Atomos and have a completely battery powered jib... I mean ProAm USA sent me Sony NP-F style battery adapters for both the monitor and the motorized head, but using the Atomos would be so much easier and better, especially with the LED battery life indicators and being able to plug into house power in a second.
Living in Florida, we get hurricanes, you bet your ass I'm going to use it to keep my phone charged during week long power outages.
I'm sure there's cheaper alternatives out there, but this one regulates voltage and keeps your devices from exploding and frying from overloads, and you can attach so much using all of the provided ports. As PC builders say, "Don't cheap out on power supplies." You run the risk of frying your stuff.
Not to mention all of the places you can put this thing, under your camera, over your camera via shoe mount, over your camera via magic arm, on the back of your 15mm/19mm rail system, on a stand, on a tripod, on a clamp... Anywhere!
B&H did a pretty good written review here