Okay, maybe we aren't hooking a nuclear power plant to our little 5 volt WIFI router, but we are damn well coming close!
So the wifi pineapple is this awesome little device that the fellows over at the Hak5 shop @hakshop sell to assist in wireless pen-testing. You can read more about the pineapple here: http://hakshop.myshopify.com/products/wifi-pineapple and pick one up for yourself at only $99.
However, while using the pineapple I was going through battery's in my little 4 AA battery pack like crazy. So I started searching for a USB battery pack and came across this: New Trent iGeek IMP99D 9900mAh External Battery Pack for $62
From there I just need a USB to Barrel cord adapter and I was good to go. I picked one up from Amazon.com for $5: StarTech.com USB2TYPEM 3 Feet USB to Type M Barrel 5V DC Power Cable This cable is a USB socket into a 2.1mm ID 5.5mm OD Barrel plug socket (with the positive inside, this is important).
I did a trial of this setup and have had it running over 3 days and counting. This is perfect for long time engagements like Rick Rolling a college, or whatever other dastardly deed you can come up with. The best part is with a rough investment of $70, I never have to buy anymore AA batteries again!