If you're putting on an event such as a Linux Fest, a film production, an organized [a]political demonstration, then you may find yourself using walkies ("walkie talkies" or "CB Radios"). Klaatu talks all about walkies in this episode; deciding whether to buy or rent, how to use them effectively, how to use them efficiently, and other matters of etiquette & protocol.
You can also listen to this walkies episode in the free audio format, ogg vorbis.