This is my shame.
Due to the way my mortgage is set up, my bank pays my municipal taxes. I was online banking this weekend and realized that in a click-down menu I could see how the tax account is doing, since municipal taxes are about to come out. Oops! My first year in the house the account didn't have enough for taxes (only 4 months worth of contributions), so they bumped the mortgage payment up a bit to fully cover the taxes. The bank never readjusted back down once the account was up to speed, and I have been paying almost $1500 too much each year.
That is being fixed, and the excess will go straight to principal, but think of all the years that money was earning some incredibly tiny rate of interest, instead of saving me mortgage interest. However, since I know I am fine with the payment each month, I will keep that payment and make sure the excess is gong to principal.
Ouch.