Here is another Microphone for your iPod called the ThumbTack which was made by SwitchEasy. The Microphone was made specially for the iPod Nano 4G and iPod touch 2G.
The ThumbTack is a ultra small microphone which has “as the name suggests” a Thumbtack design. The plug is gold-plated and is non-corrosive, plus it will work with third party apps for your iPod. The thumbtack is available in Red, Black and White at $12.99 and $3 shipping and handling per unit.