I received my Planex IEEE802.11n Draft2.0/g/b Compatible Wireless LAN micro USB Adapter in the mail today and with a bit of self-inflicted frustration, finally managed to have it appear on the iMac.
If you happen to have an older Mac -- like I just purchased -- without an airport card, this is a perfect solution. You don't have to open the case (lots of people would be freaked out by this), it eventually installs, and you've got a great wireless machine.
A friend of mine wants it as a starter machine, and was completely bummed out when I told him that it didn't have a wifi connection. This was a great solution as far as I was concerned.
Now all I have to do is figure out how to upgrade the hard drive. That's going to involve money again, isn't it? Crap. Oh well, you only live once.