I have made a piece of software that can do all sorts of electronic calculations. The software is free.
Convert between color codes and numeric values for many types of components.
Analyze or design an air core inductor
Color/wavelength of leds and design of circuits to drive leds from DC or AC
Timing and curves, usefull when programming software uart's and IR rx/tx.
Calculate crc, checksum and modulus for datablocks, can also analyze a datablock for what checksum/crc was used
Analyze and design power supplies with 78xx and LM317 style regulators
Calculates Fo for RC, RL, RLC circuits
Calculates for PT100, NTC and all types of thermocouples
The software is here:
Th site includes screen shoots and descriptions of many of the functions.