My Financial Shepherd
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CALCULATORS

Debt Management Plan
www.quicken.com/planning/debt/debt_planner

Car Financing
www.edmunds.com

Education Funding
There are a lot of great calculators related to college funding including expected family contribution.
www.finaid.org/calculators  

Retirement Projection
This is a great calculator developed by Bill Sholar.  It takes the information that you provide and projects by percentage how likely you are to reach your retirement goals given your current and future savings by comparing your expected return on investments to historical returns.  Be sure to follow the link on their website to help you calculate your future expenses.
http://firecalc.com  

This calculator is more simple to use, it assumes a constant rate of return (which you choose) on your investments.  You can enter both taxable and tax-deferred accounts as well as  consider the effect of taxes.  It will estimate how much money you can withdraw over the time period you choose. 
http://i-orp.com

Required Minimum Distribution
www.calctools.com/newrmd.htm

Mortgage Calculators
www.decisionaide.com
This site has advanced mortgage calculators (e.g. refinance an ARM to a fixed mortgage).      

IRS Form 1040 Tax Estimate
http://turbotax.intuit.com/tax-tools

Paystub Tax Withholding
IRS Paystub Withholding Calculator

Alternative Minimum Tax (AMT) Assistant
IRS AMT Calculator