Plantronics DSP 550
Back in early 2002 I voiced an entire 2 hour AM radio show using a Plantronics USB headset microphone and an old 166 MHz PC. Not ideal recording conditions, but the show actually sounded quite good considering the limitations of available gear.
Over the past couple of weeks, I've been testing out the new Plantronics 550 DSP Ultimate Performance Headset. So far I'm impressed. The earphones offer great audio output from a comfortable design that I can wear without getting annoyed that I have headphones on. I get up from my computer often enough that I never kept them on to the point where I was feeling any ear discomfort. The microphone positioning is flexible to the point where you can get a good microphone position without getting too much plosive impact from P and B sounds. While there's noise cancellation built-in, the microphone is still extremely sensitive and picks up things like the click-clack of fingers on a keyboard, which means you need to eliminate extraneous noise if you're recording audio for any kind of published project. I don't have a way to test latency in lab conditions, but there seems to be almost no noticeable lag.
Overall, I'm giving the 550 DSP a big thumbs up for both speech recognition tasks and for doing things like solo podcasting efforts. You'll get great sounding audio from recording directly to a PC application like Audacity or Adobe Audition, speech recognition apps will effectively capture your voice and if you use voice applications like Skype, your friends will be pleasantly surprised at how well your audio sounds. At $60 from most online retailers, this headset microphone combination is a steal.