Just a quick tip for a narrow segment of the population.
If you have an Airport Extreme* (APX), and you want to refer to the other machines on your network by name instead of by IP address, set the "Computer name" in System Preferences -> Sharing. That computer will then be available at "(computer name).local".
The APX may need to restart to recognize the new name, which is done by going to "Base Station" menu -> "Restart..." in the Airport Utilities tool (in the /Applications/Utilities folder).
If you don't want to add ".local" on the end, go into System Preferences -> Network, Airport, Advanced..., DNS tab, then add "local" to the search domains. Looks like this has to be done on each computer.
* One sidenote -- the APX is a $179 wireless 802.11 dual-band (g and n) router. I absolutely refused to pay $179 for a device that I can get from Linksys or Belkin for $59. Until, that is, after 3 years of irritating reboots (and trying to talk my wife through reboots), painful setups, and irregular behavior, I finally had enough and bought the APX. I had always figured I just wasn't a networking guy, but the manual setup of the Apple router required understanding of all the same concepts and it worked consistently right out of the box. Sorry Linksys and Belkin, try again.