Credit Federal Free Budget Calculator to help manage expenses. Also includes a Savings Calculator to determine interest earnings. 

I like this because it’s simple, and includes  several different calculators all bundled in one.  You can calculate your monthly budget, see how interest accrues when saving, and different loan calculators such as auto loans and mortgages.  This would not be recommended for managing cash flow long term, but its perfect for someone just getting started on trying to understand their current financial situaion.

This post via the Freedom Debt Management blog, an educational resource to help you gain control of your debt management and finances.

Free Debt Management Software