We found an excellent FREE debt calculator created by Vertex42.com. It allows you to input all of your outstanding debts along with their corresponding interest rates and your minimum monthly payments. It then calculates how much you could be saving with the avalanche method. Or it can visualize your pay-off dates for either Debt payment method. Spreadsheets are available in a variety of formats (.xsl, .csv, google doc etc,.)
Click here for download.