Debt Reduction Calculator by vertex42.com (compare avalanche, snowball, and customized order of paydown)
Free Calculators for Tax Witholding, Credit Card Repayment, Debt Payoff etc.
A variety of financial calculators: Cash flow, college,credit and debt, home & mortgage, taxation (US), insurance, paycheck & benefit, qualified plans, retirement, savings, investment, automotive and business.
A debt paydown calculator that allows you to create a log-in to save your information. Includes extra payments (scheduled and one-off).
Stash Builderrough math for how many years to retirement
Vanguard's Nest Egg Calculator
cFIRESim Retirement Calculator
Deciding whether to use an HSA and High Deductible Health Plan by /u/HSASpreadsheetGuy
Portfolio Summary by /u/wijwijwij uses Google Finance for updates