How many calories am I really burning...is there any way to tell?

I would just like to know how many calories I am really burning during exercise. Someone has probably asked this question before and I just missed it. Anyway, my treadmill says 140 and CC says 74 and my sweat glands say 300- what the*&%$ is going on here?

I've seen a bunch of people mention a Polar something or other and have been curiously interested myself.

The Polar something or other is a heart rate monitor.  I have one myself and I think they are pretty accurate, if you get a good one.  I think I spent about $100 on mine.  The nice thing about these is that they can transmit your heart rate to the tread mill (or whatever cardio equipment you are using) so it is displayed there and you don't have to hold on the whole time.  Mine came with a wrist watch that tracks the time spent working out, calories burned, heart rate, average heart rate, and max heart rate.  Its great for making sure you are staying in the desired heart rate zone. 

The only other way I know of to track Calories burned is with a Body Bugg.  These can be pretty expensive ($300 - $400) but are supposed to be pretty accurate (I think you can find them used on Ebay).  The Body Bugg tracks your Daily Calories burned, so you wear it all day.  There is a monitor that goes around your arm and it keeps track of what you've burned throughout the day by tracking several things but not heart rate.  Then you download the data from your Body Bugg to the computer and through the online program you can track your daily calories in versus calories out. 

WOW! I guess you know your stuff! Thanks that was a huge help!

hope2577, i have a polarf11.  it's quite handy and all, but keep in mind that all these numbers are just estimations.  the heart rate monitor can't accurately measure your vo2max (though some models try), and it doesn't know your body fat percentage.  that said, i use the one i have.  unfortunately, its numbers tend to be WAY lower than the ones reflected on the cardio machines (usually 2/3, from my experience).