Wired news is running an article describing some basic information about the ham radio hobby.

http://www.wired.com/news/digiwood/0,1412,67615,00.html

An eham.net article today pointed out the you don't need alot of power to transmit a great distance. Previous records unknown, the new record set by Bill Tippett, W4ZV, of New London, NC. He was able to copy a cw (Morse code) beacon on the 80 meter band (3.5mhz) from Wappingers Falls, NY a total of 547 miles. What makes this so amazing is that the beacon was only transmitting at a peak wattage of .0000406 (40 millionths of a watt). To put this is perspective a standard linksys access point(wap11) transmitts at peak power of .1 watts and has a range of about 1000 meters. The record breaking stations was able copy aouther stations transmiting roughly 60,000 times less power over 860% farther.

To learn more goto:
http://www.eham.net/articles/9982

Ever wonder if you're exposing yourself to dangerous amounts of RF radiation when using an RF transciever? Well, with this handy java calculator you can calculate RF field density estimatations.

See the Amateur Radio RF Safety Calculator from Utexas.edu