Anyone who has ever owned (or still owns) a police/fire scanner and enjoys aviation can appreciate this: LiveATC.net allows listeners to monitor aircraft and airport transmissions throughout the world right from the comfort your own home.San Francisco Tower and NorCal approach are two local channels available. During inclement weather, i've heard some interesting conversations between pilots and air traffic control. Beyond the Bay Area, you can monitor airport frequencies throughout the United States and world. Looks like Botswana was recently added. Visit LiveATC.net and their Top 30 list.