Federal Reserve Bank
Federal Reserve Bank of Minneapolis: Cpi Calculator Information
Provides a consumer price index (CPI) calculator. Enter in a dollar and year and it will tell you how much it is worth today. Also includes good links to additional CPI information resources, and a link to a mobile app.
Other
Economic History Services: Measuring Worth
Students investigate the worth of a (US) dollar or a (British) pound, the relative value, purchasing power, and inflation rates. The resource consists of explanations, calculators, measures of worth, and data sets.