Powering the Adventurous Geek?

Xochi77 asks: "As a Geek and a Backpacker, my laptop travels where ever I go, but now that I'm planning a trip through remote regions of South America and Africa, I'm starting to wonder where I'm going to get my power from. How has the Slashdot community dealt with powering high-tech gear in third world countries? I'm especially interested in alternative power sources, like solar cells and wind-up generators etc, but they will have to fit in my backpack!"