There's a slashdot article about the digipeater on the ISS. http://slashdot.org/article.pl?sid=01/04/12/2054254&mode=thread You basically send packets up and it repeats them back down. More technical details on http://www.ariss.net It's a low-volume thing, and only works when the space station is visible ( http://www.heavens-above.com/ to locate the station ) but would be an interesting hack for remailers. There are already a few repeaters that take the packet radio downlink and mirror it to the Internet. Heavens-above.com also has a list of a few dozen amateur satellites, though it doesn't say which if any are used for packet data as opposed to voice.