Power pack for camping?

I'm going to be in plane camping at Oshkosh this year, and I'm wondering
how I'm going to keep my camera batteries and iPod charged. I know from
harsh experience that keeping the airplane master on to use a cigarette
lighter adaptor runs down the plane battery pretty damn fast, so that's
not a good idea. Is there such a thing as a battery powered portable
generator?

--
Paul Tomblin http://xcski.com/blogs/pt/
Quality Control, n.:
The process of testing one out of every 1,000 units coming off
a production line to make sure that at least one out of 100 works.