This is indeed the cheap solution, which would work for 99% of users, unfortunately, in my very specific case, I need something that would provide me over 10 if not 20 hours of power, I could certainly buy 5 to 10 additional batteries but there's got to be some device that would do this better.

Also, buying spare batteries doesn't help charging other electronic components, which would be a nice plus here. I've seen some posts on this forum about people hacking an external battery kit for 770 or whom found some sub-$25 adapters that gives them an extra hour or two, but what I'm looking for is some more heavy-duty power source. Something that obsoletes the included nokia power adapter. Something that makes this irrelevant: "Oh I can't work on this, the file's on my laptop and the battery's dead, let's wait until we get to the new airport so I can wifi the file over."