http://www.amazon.com/Taylor-TruTemp-Digital-Cooking-Thermometer/dp/B0001BFJ54
Put it in your pot set to the strike or (close to) boiling temp, then go do something else (nearby) until it beeps. Big time saver for me since my office is beside where I brew.
That's definitely a concern. I use a basic kitchen thermometer with an alarm to make sure that I don't overshoot/undershoot my mash temps