Skype on your Mac in Windows & OS X - Griffin iMic
The aptly named Griffin iMic gives you one feature which it seems all recent portable macs are lacking - support for a non-powered external microphone. As an added bonus, it works in Windows too! If you've got an Intel Mac and are using bootcamp to load windows, this fixes your issues with your soundcard for a minimal $29.99.
OS X Review
In OS X, it is pretty straightforward - just plug it in to the USB port and select it in your sound preferences. You can use the iMic for sound output on all sounds, or just in Skype.
It works very well as a consumer level device if you want to conference call with friends and family, or produce your own podcast. It also has stereo mic inputs so if you have a fancy stereo mic or want to use a splitter to mic a room in stereo, you can do that too! Im thinking about using it as an inexpensive way to do a podcast. There are two benefits using my external headset with this device over the internal mic. One is that people dont hear when I am typing and the other is that it my headset mic doesnt pick up all the background noise in the room too like the MacBook's mic does.\
Windows Review
In Windows XP, it's as easy as OS X. Just plug in the iMic and Windows recognizes it as an external sound input. Go into the Sounds and Audio Devices properties in the control panel. Under the "Audio" tab, you can select the iMic USB audio system for both Sound Playback and Sound recording.
Capturing sound with the iMic seems to be pretty reasonable. I have my Sennheiser PC150 headphones plugged in and my fellow skypers tell me I come in loud and clear. What's cool with skype in Windows is you can tell it to ring on your external speakers, but play back audio on the headset. This feature is not yet built into skype for Mac. We're only on 1.6 whereas windows is at 2.0 :( This gadget truly adds value to my Mac setup and although it tries to look ipod-ish, it's not that stylish. I would recommend it though to anyone sick of dealing with the soundcard in Bootcamp Windows and anyone else with a MacBook who wants to use Skype or other conference software.