I have looked around now and again for a mortgage calculator that I like and I finally found one. So I'm going to share it with you.
http://www.apimagazine.com.au/calculators/mortgage/
This calculator will show you how much your monthly payments will be including your insurance and taxes. It will show you how much interest you're going to pay if you just make your house payments.
Under that is the part that is eye opening. You can put in an amount that you want to add to your house payment each month and it will tell you how much money you'll save and how much quicker your house will be paid off. This calculator has a couple features that I haven't found on others. You can add the extra money at any point in the calculation. If you have been paying on your mortgage for 3 years, you can tell the program to start adding extra money at month 37 and note how it changes things.
It also has a pretty blue and green graph. =)
Here's a couple quick examples but I really encourage you to go to the site and play around yourself.
If you have a $200,000 mortgage at 6% and you pay an extra $100 a month from the start, you will save $50,000 and pay off the loan 5.5 years early.
If you can pay an extra $250 a month from the start, you'll save $91,000 and pay it off 10 years early.
Just about everyone can get to the point where they can pay these amounts. In fact, most people with houses can probably get to where they can add an extra $1,000 a month to their house payment. Play with the calculator and see if that doesn't encourage you to put some extra money where it counts. Paying a little bit extra saves you thousands of dollars and years and years of your time.