MicFlex
The MicFlex, from MacMice, is a prime-time player in the realm of external microphones. While geared to the Mac gadgeteer, it is a platform independent USB powered microphone, at home with Windows as well as OS X.
In my tests, I used the MicFlex with a titanium Powerbook. Without a doubt, the performance of the MicFlex far exceeds the internal microphone. The bullet-like enclosure focuses the input sharply, eliminating most ambient noise. The goose-neck adjustment aperture bends and transforms with ease, allowing quick-change placement. The base is heavy and substantial, keeping the microphone stable and vibration-free.
The bendable neck can be removed from the base, and placed directly in a USB port for travel uses. That's a perfect solution, because I found that the perfect application for the MicFlex was iChat AV. Long distance voice and video chat were enhanced exponentially by the use of the MicFlex. My conversation pals said that the clarity was a noticeable upgrade from the internal microphone.
MicFlex is also an excellent companion for internet radio broadcasting or for recording voice memos. While MacMice encourages the use of the MicFlex with Garageband, it won't be replacing my Shure microphone anytime soon. But, for casual demos, it works well enough.
If ten dollars were shaved from the price, the MicFlex would be a must-own peripheral for any active Mac user. At its current price point, it is a worthwhile upgrade for radio hobbyists and frequent audio chatters.