Salvage Checklist

Printers / Scanners / Photocopiers

 * Stepper motors
 * Belts
 * Gears
 * Slides
 * Optical encoders

PCs

 * ATX power supplies
 * Ribbon cables

Cars

 * Alternator
 * Windscreen wiper motors
 * Central Door locking mechanism:
 * Low current triggered relay (located in dashboard / fusebox)
 * Lock actuator (located in door)
 * (more info: http://www.youtube.com/watch?v=uIbkLjjlMV8)
 * Battery
 * Add more

Bikes

 * Add stuff here

TVs

 * Add stuff here

Microwave ovens

 * Add stuff here

Toasters

 * Add stuff here

Electronics
If you feel like desoldering lots of parts, go for it, but surface mounted stuff is harder to reuse than through-hole stuff. Look in particular for commonly used general purpose stuff like 555 timers and capacitors.
 * 555 timer - http://en.wikipedia.org/wiki/555_timer_IC