The Bank Rate Monitor posts current interest rates for U.S. mortgages, home equity loans, bank CDs, credit cards and consumer loans based on surveys of lending institutions. Most data can be viewed nationally or by city/region. Consumer Action and CardWeb do credit card rates.
The Federal Reserve's Statistical Release H.15, "Selected Interest Rates" lists many interest rates, including Federal funds rate, CD rates, Eurodollar Deposit rates, prime rates, discount rates and U.S. government securities rates. The Federal Reserve's Board of Governors posts H. 15s back to the mid-1990s (www.federalreserve.gov/releases/h15/data.htm).
Historical interest rates for Treasury Securities set at Treasury actions are posted on TreasuryDirect.gov. Commercial Paper and market rates for Treasury Securities are included in the H. 15s published by the Federal Reserve.
Certain historical market interest rates are available from SunGard (formerly Tradeline), available through Dialog or Lexis (you might want to call customer service first).
Add-on Interest Rates: Add-on interest rates are calculated at the beginning of a loan, rather than over the term of the loan. There are tables that translate add-on rates into the "simple interest" equivalents and vice versa. One source for these tables is the Rate Translator booklet sold as PUB #825 by the Financial Publishing Company.
Auto Loans: See "Automobiles."
Compound Interest: See "Future Value."
Consumer Credit: Federal & state laws regulating the interest rates on consumer credit are republished in CCH's Consumer Credit Guide, which is available as a looseleaf, on Lexis (CCH;CCHFIN) and on CCH's subscription-based Intelliconnect. See also "Usury."
Foreign: Foreign countries' interest rates going back about five years are published in the IMF's International Financial Statistics.
Mortgage Rates: Mortgage-related rates are posted by HSH Associates, Bank Rate Monitor, QuickenMortgage "Real Estate."
Municipals: Interest rates for municipal bonds and other municipal securities, including auction rate securities and variable rate demand obligations, are available on EMMA as well. See also "Municipal Bonds."
Taxable Equivalent Yields: What's a tax-free interest rate worth? You can figure the taxable equivalent using calculators posted by CNN/Money, Morgan Stanley and others.