I am a photographer who takes a lot of pictures (16mb) and doesnt want to keep a large collection of flash cards. Is there a type of device that has a hard drive and can operate without a power cable with the ability to read flash cards? If so, what is it called?

Thanks for the response, but I was actually looking for something to be used far from a laptop or ac power. I actually just found it. If anyone wants something like this, heres a link:
http://www.newegg.com/Product/Prod [...] 6822110001