I've got this:
http://www.bestbuy.ca/en-CA/product/...12853a0e56en02
Not so much for the sake of battery life but I like how it helps keep things clean and easy. Clicking the controller in to charge is so much quicker than plugging in even if it's a minor thing. Plus the USB cord I save for my wireless headset/phone.
Having 2 controllers makes the battery life not a big deal though I do wish it lasted more.