
For some unknown reason, microphone explorations have been foist upon me of late. I have no idea why! Sort of odd, really...
But, I recently was introduced to SwitchEasy's ThumbTacks micro-microphone. This little microphone (only slightly larger than an actual thumbtack and of a very similar shape) is inexpensive and easy to use. You just plug it into the headphone jack of the iPod Touch 2G or an iPod Nano 4G.
SwitchEasy states that they carefully selected the actual microphone unit to capture quality audio at a reasonable price. And how does a list price of $12.99 (as of this writing) sound for an iPod microphone? I decided I would take one out on a test drive. Below you will find a recording using three microphones: the Shure MPA-3C Music Phone Adapter for iPhone (used on my iPod Touch—not on my iPhone), Macally's iPod Audio Recorder Black (IP-A181), and the SwitchEasy SW-TT-B ThumbTacks Micro-Microphone. You can check out the price of each at the links above. (The ThumbTack is less than half the price.)
The test: in a single recording using the iTalk application (Griffin offers a free version) on my iPod Touch, attach each mic, one at a time, place the iPod Touch in my shirt pocket, say which mic I was using, read a sentence, take the iPod out of my pocket, place it on pause, change mics. I added a sound clip at the beginning, end and between each sentence to make the recording a little more interesting.
I clipped the Shure mic on my shirt on the same horizontal line as the top of my shirt pocket. The Shure mic was still, however, maybe less than an 1 inch closer to my mouth as it was near the shirt buttons and not the shirt pocket.
I was rather surprised by the outcome. But I'll let you hear it for yourself (1 minute, 40 seconds).

I have always preferred the Shure sound quality. It's excellent and in stereo. The sound wave from the Macally is clipped and little can be done to correct clipped digital audio. I suspect that if you only heard the recording from the ThumbTack, you would just turn up the volume a little and be a happy camper. (I also noticed that since this mic is so small, the ThumbTack was a little below the top of my shirt pocket, which would block some of the sound coming at it. I'm fairly confident I would have achieved different results had I held the iPod Touch in my hand in front of my face.
So, for me, in this simple, unscientific test, the Shure has the richest sound quality, but the TumbTack, at less than half the price, isn't a bad choice at all. For some reason, the Macally clipped the digital audio and achieved a poor sound quality as a result.
In the example below, I normalized the audio from the ThumbTack. (This is easily accomplished in GarageBand or in Audacity.) The volume of the sound is therefore significantly boosted, but with the desired audio comes a minor amount of background hiss, which also got boosted by the normalization. One could spend an extra minute and remove much of the hiss. I didn't. (41 seconds)

So my positive take on the ThumbTack: I really like the price. (In fact, I am unaware of a less expensive option of any quality.) The sound quality is more than just satisfactory for school projects; it's actually good. The mic appears durable with no wires to wear out or get tangled. It's simple to plug in and out. The size requires little storage space for a class set.
My negatives on the ThumbTack: It's so small and cute it could easily sprout legs and disappear. Kids would love to have one of these. Is it a choking hazard for really young children?
Bottom line: You can afford a class set of these and achieve good sound results!
Disclaimer: I am not endorsing or recommending any product. I am not being paid to say anything about any of these products. Your results may vary.