Inductor colour code calculator
Online colour-band calculator — the inductance value from the markings, including the military standard.
Inductive reactance calculator
Online reactance calculator — X = 2πfL with careful unit conversion.
Conical Tesla coil calculator
Online conical coil calculator — inductance computed numerically by Maxwell's method instead of Wheeler's formulas.
Wire-above-plane inductance calculator
Online wire-above-ground calculator — the inductance and characteristic impedance of a length of line at UHF.