Current:
Filament lamp (indicator lamp)
Vacuum fluorescent display (VFD) (preformed characters, 7 segment, starburst)
Cathode ray tube (CRT) (dot matrix scan, radial scan (e.g. radar), arbitrary scan (e.g. oscilloscope)) (monochrome & colour)
LCD (preformed characters, dot matrix) (passive, TFT) (monochrome, colour)
Neon (individual, 7 segment display)
LED (individual, 7 segment display, starburst display, dot matrix)
Flap indicator (numeric, preprinted messages)
Plasma display (dot matrix)
Obsolete:
Incandescent filament 7 segment display (aka 'Numitron')
Nixie Tube
Dekatron (aka glow transfer tube)
Magic eye tube indicator
Penetron (a 2 colour see-through CRT)