Ever find yourself on a job site with a low battery in your phone, and no working outlet anywhere? If you have the PoweriSite in your pocket, there’s still hope for you. Plug it into the batteries that power your cordless tools, and plug a USB charger right into it. Just like that, you’ll be ready to make calls again in no time. It’s $18 on pre-order with delivery later this year.
[ Product Page ] VIA [ Werd ]
Dewalt already makes one of these themselves
http://dewalt.com/tools/cordless-batteries-dcb090.aspx
Not bad for $18..