I'm not sure what kind of BBQ you are into, but my dad and I do quite a few competitions every year, and the temperature inside the smoker itself is more valuable than the temperature of your meat. It's easier to consistently get your smoker temperature to what you want than attempting to cook your meat at specific temperatures, considering no piece of meat is alike another. Obviously we check the internal temp to make sure it's safe, but it's easier to keep the smoker at 250f for 4 hours than to make sure your internal temperature stays at whatever degree for 4 hours.

I would absolutely recommend any type of K-type thermocouple, because they can handle the heat that the BBQ will spit out. In fact, the one I used for testing and initial development was directly from Adafruit[0]. It works well, it's just a little flimsy. It's not USB, however.

[0] http://www.adafruit.com/products/269