What should my heartrate be during exercise?

I googled this question and here's a webpage that was very helpful. I just recently bought a Heart Rate Monitor and was able to monitor my exercise during a workout. I found out that I was between 60-85% throughout my workout so I was doing good during exercise. By the way, the heart rate monitor always gives me the amount of calories I burned during the workout, so no more guessimating!
Here's a webpage for all of you who might have this pondering question! http://www.medicinenet.com/exercise/page4.htm