P-channel JFET
Bucket brigade device
Vactrol (LDR coupled with an LED to make a current controlled resistor)
FET analog optocoupler
Double photodiode analog optocoupler
Depetion mode MOSFET
Unbuffered CMOS logic (e.g. CD4007)
FPAA
Quartz window EPROM as an image sensor
IGBT in the linear region
LED as photodiode or photovoltaic generator
Clamp meter as a compass
Motor as a speaker