Just spent a couple minutes in CashFlow and I'm looking forward using it more. I set up an account with Mint a while ago hoping I could do something similar but this is just so much better for what I wanted to do.
I am a heavy Mint user myself. I track my past expenses using their tools. I use CashFlow to predict my future balances. Just remember to manually update you current balances (bank, credit card) on CashFlow any time you want to do any form of analysis. It takes a minute or two for me to update my balances (login to Mint, refresh, copy-paste balances).