I've been doing it for a long time: several times over the years I've emptied a big jar of coins and cashed out $200 to $350 at my local bank.
Wouldn't it be nice if there was a program, preferably FREE, that tracked this "found money" (or the money your kid sticks in his or her piggy-bank)? Well, thankfully, DonationCoder member caddo requested just such an app and, intrigued, I created it. I wrote a program in mid-2011 that has this functionality.
The program allows you to keep track of money that you find -- under your car seat, in the washing machine, etc. Features record creation, saving, editing.
You can even search against criteria ("show me any records in which the number of pennies is less than six", or "show me any records in which the number of one-dollar bills is exactly equal to three"). Use it for its original intended purpose, or as a digital piggy bank.
Here is a six-minute YouTube vid showing how the program is used.