I think IF (
http://www.if.com/
) have a demo on their site. My bank (Clydesdale) actually sent me a cd into which I could key my own data, and I never did!! The basis is that you "pool" all your debts such as mortgage, credit card, loans etc and savings, and calculate interest, daily, on your outstanding balance, at your mortgage rate which is generally lower than all other debts, and higher than any savings rates. Additionally, since most people pay their salary into their current account, as the month goes by the money (or lack of it) reduces as the bills are paid, until the next payday. Any positive balance is usually paid interest at some measly level like 0.1%, and so by using it to reduce your mortgage, albeit temporarily, you effectively earn interest at your mortgage rate. So it really suits anyone who has a mortgage and any other type of account. If you need more info, post another question and good luck.