Calculations and Conversion Tools  

Calculator.com http://www.calculator.com/

A directory of online calculators and calculating tools. Both numeric and scientific calculators as well as unit and currency converters.

Conversion Calculator http://www.infoplease.com/pages/unitconversion.html

InfoPlease conversion page for weights & measures.

The Inflation Calculator http://www.westegg.com/inflation/

Enter any dollar amount and compare its value during any two years between 1800 and 1998. Conversion Tools

Common Weights And Measures http://chemistry.berkeley.edu/links/weights/index.html

From the College of Chemistry at UC Berkeley, this site includes mathematical notation for orders of magnitude, metric prefixes, and common U.S. and metric equivalents.

A Dictionary of Measures, Units and Conversions http://www.ex.ac.uk/cimt/dictunit/dictunit.htm

A summary of measurement systems from around the world with descriptions of units of measure that can be chosen from subject oriented or alphabetical lists. Also includes the standard unit, S.I. ('Systeme International'), and conversion tables for it.

megaConverter http://www.megaconverter.com/Mega2/

megaConverter.com is an ever-growing set of weights, measures and units conversion/calculation modules. For just about anything you can think of, megaConverter can show you its equivalent. Currency

OANDA http://www.oanda.com/

A currency converter which contains the exchange rates for 164 currencies. Also includes historical currency exchange rates and can make forcasts for global markets

Online Conversion http://www.onlineconversion.com/

Conversions for everything from science to cooking.

The Universal Currency Converter http://www.xe.com/ucc/

Interactive online currency converter that allows you to put in a dollar amount then select the two currencies to compare.