I purchased this IMP500 from New Trent to charge my Nook Classic. I don't own a NookColor (yet), but you can check it out...I think it should work for you.
Edited to add: I suggest you read this thread:
Now I'm not so sure the IMP500 would work on a NookColor. Sorry.
I am looking for a portable charger that is under $100 but has the capacity to charge my color nook when I don't have a 120v or car plug handy. I would use this on planes or camping. any thoughts?
You need to get a plane - cigarettle lighter adapter. The Nook car charger should work fine on an aircraft using the adapter.
I can't post a link here, but if you do a google search on "aircraft plug to 12v" you'll find several in the $12 price range. And the nook 12v car charger is $25 here.
I connected my NC to my ThinkPad laptop with the standard USB cable and I can confirm that it would charge the NC, slowly.
I know nothing about this company, which I found in a Google search. I am seriously thinking of getting one of their products myself, especially after recent events have demonstrated the value of portable power. As it happens, unlike more than half the folks here in Connecticut my condo never lost power in the storm. My backup plan in the event of extended power outage had been to use my Nook Color and MiFi 3G WiFi hub from my car with the B&N stock car charger. But that would have required going to the car for power. If I get one of these gadgets then I would be able to use it indoors.
Edited to add: I have ordered one of their products. What I particularly like about this option is that I can use my existing car chargers for my various devices including NC, and therefore it is electrically exactly the same as if I were using it in my car so there can be no compatibility issues.
I made my own using a Radio Shack 8 cell AA battery holder, A Belkin Cigar Lighter USB Adaptor and some AA rechargable batteries. Recharge the batteries and your Nook before your trip and just keep the Nook plugged into the USB Adaptor while you're using the Nook. It extends the time you can use the Nook dramatically.
Send me an email and I'll send you pictures of the thing in action.