Boy, Oh Boy -- have Online Calculators proliferated on the Internet!
Here are links to a vast number of such calculators, for everything from
Home Mortgages to Solar Flux to Electronic Circuit design and analysis.
Martindale's Reference Center --
A multitude of online calculators (over 17,000), including many scientific and mathematic calculators,
plus hundreds of others in a wide variety of fields, from financial to agricultural.
Extensive variety of software calculators collected in one directory.