Calculators

Calculation and Conversion Tools     -  "Websites that assist with mathematical calculations, including online calculators and conversion dictionaries and tables."
Calculator Links     -  Calculator links by Calculator.org
Calculator.com     -  Online calculator collection: standard, fractions, scientific, graphing, mortgage, loan, lease, currency, conversion, ...
Convert It!     -  Online conversion tables for areas, energy, pressure, volume, ...
iFigure     -  "Online calculators for house and home, car and travel, money and personal finance, health and medical, business and management, science and engineering, and mathematics and statistics."
Interactive Statistical Calculation Pages     -  "A large collection of links to interactive web pages that perform statistical calculations."
JavaScript Pocket Computer for Physics     -  Comprehensive scientific and physics calculator.
Martindale's Calculators Online     -  Links to over 15,000 online calculators.
megaCalculator     -  "megaCalculator is a totally web-based scientific calculator capable of practically any common calculator function and many uncommon functions. It is continually growing and being improved."
MegaConverter 2     -  "This is an all new version of your favorite educational and research site, giving you a new, easier to use interface, with more converters, more features and quicker access."
Network Calculators     -  "Free TCP/IP Network Calculators. Includes web-based Subnet, Supernet and network / node calculators."
Rolf's Scientific Calculator     -  "A fully featured scientific calculator with proper operator precedence is implemented, including trig functions and logarithms, factorials, 12 levels of parentheses, logs to base 2 (a handy function for information entropists!), bitwise logical operators, hex, octal, binary and ascii display. There are actually two separate calculators with different keypad layouts, a scientific calculator and one for logical operations. To switch from scientific to logical mode press the 'HEX' but note that pressing 'DEC' once just changes the displayed value to decimal. You have to press the 'DEC' key a second time to return to scientific mode!"