Hey there, everyone! Today I'd like to briefly explain how to do something that very few people who own a Mac actually realize they can do: create a wireless access point using only your Mac.
Now, obviously there are two prerequisites for this: you must have a Mac with a wireless network card in it (every modern Mac does, with the exception of the Mac Pro), and the mac you want to turn into an access point must have an internet connection (through Ethernet, not through wireless). If you have these two prerequisites, you're ready to turn your $599 Mac Mini into not only a great computer, but also a fully functional wireless router, complete with SSID broadcast and built-in DHCP server!
It's actually quite simple. On your Mac, open up System Preferences. About halfway down the window, you should see a folder called "Sharing;" click it. Once you do, you'll be presented with several options; you can leave pretty much everything here at the default, but you'll want to ensure that "Share your Internet connection from:" is set to Ethernet, and "To computers using:" is set to Airport. Once you've done this, click "Airport options." You will be presented with a dialog box where you can enter the SSID, password (if any), and security type (if any). Once you've done this, click "OK." You're now all ready to "flip the switch" and turn your Mac into a router! Simply click the checkbox next to "Internet Sharing" in the left pane of the System Preferences window. You'll be asked if you're sure you want to do this (and understand the potential ramifications of doing so). Click "Start," and you're ready to go!
It's worth noting that these steps are for Mac OS X Leopard; this is possible to do with Tiger as well, but the dialog box looks slightly different. It's also important to note that this access point is fully compatible with all Macs, as well as Windows and Linux based PCs. Enjoy!
My name is Fooruman (aka Black Ninja, aka Dain), and I approve of this post.