Imagine a sheet of paper the size of a football field but infinitesimally thin. Now, fold it in half. Fold it in half again. Continue folding it in half until it's the size of a postage stamp. You now have something with the surface area of a football field that you can easily fit in your wallet.

fun fact: there are a few miles of metal interconnect (wires) inside the microprocessor chip you are using right now [1].

[1] www.itrs.net/Links/2007ITRS/2007_Chapters/2007_Interconnect.pdf

Your lungs have roughly half the surface area of a tennis court. Much internal folding.

http://books.google.com/books?id=pAuiWvNHwZcC&pg=PA120&lpg=P...

Activated carbon filters are another material with a phenomenal surface area.

ask Mandelbrot

there's no magic here. For example, activated carbon [1] has a surface of 500 m^2 per gram. It's just a very porous structure.

[1] http://en.wikipedia.org/wiki/Activated_carbon