Blue Microphones (http://bluemic.com/snowball/), the same company that produces the popular Snowball line of what the company terms “professional”-sounding USB mics, has come out with a new microphone in the sub $100.00 USB category. Called the Yeti, this microphone retails for $150, but can be found for around $100.00 (http://www.amazon.com/Blue-Microphones-Yeti-USB-Microphone/dp/B002VA464S).
The main distinguishing feature of this microphone appears to be the inclusion of a built-in headphone amp (with volume control), so that you can monitor your voice in real time, and in doing so up the quality of your delivery style.
Some additional features include (according to many reviews) significantly improved audio quality over other popular USB mics (including other Blue mics), and four different polar pattern settings (Cardioid, Stereo, Bidirectional and Omnidirectional), and a simple and solid build. On the negative side, this is a very large microphone, at about a foot high, and one review I read noted that maybe a couple of the knobs are a little flimsy.
There is a pro version of this microphone that is 2.5x the price, but includes professional recording via analog XLR, a separate analog circuit path, and better sampling rates and frequency response.