Google Mortgage Button. They are a neat thing to have. It is truly a life-changer to be without a mortgage. Think of it this way. Whatever your interest was on the mortgage, paying it off early is like getting a *guaranteed* interest rate on savings.
I think mortgage calculators are handy things to have. When I bought my first house, I created an excel file that calculated the mortgage (the table format, I forget what it is called) and the total amount I'd pay for the house just paying the minimum. Then I noticed that the amount to equity in the first payments were minimal and that if I just added that extra to the payment, I would be skipping an entire payment at the end! I kept that file and every time I added extra to the mortgage I'd update the file and it was a huge mental boost. I ended up paying it off in 7 years. I think the mental boost of using the mortgage file was critical to that because otherwise it just seems so overwhelming. I have a friend for example that doesn't think she'll ever be without a *car* payment.