Microwave ovens are dangerous to take apart even if you know what you are doing...those massive caps can zap you long after the machine has been unplugged...but they contain a wealth of useful parts for safety qualified engineers to loot.
One of the most interesting parts to my mind (of the many in these devices) is the piezo-electric component. You can use it to make a crystal earpiece if you remove it very gently. I should add that I have never looted a microwave oven myself because the super-caps are a bit scary.
Broken printers are a good second. Stepper motors can be expensive to buy from new and great for robotics projects. Some nice caps in there as well.
Last but not least, broken old motherboards...seemingly uninteresting because of all the dinky micro-components (...note that you can remove and re-solder even tiny surface mount components if you have a hot air gun and solder paste) also have lots of high end electrolytic capacitors great for the parts bin.
The really old motherboards (such as Pentium II Dell motherboards for example...photo below)
air cushion machine have high end golden colored heat sinks. Magnificent for quality DIY amplifiers. These heat-sinks might cost £60 or more on Ebay ($100) from new . Massive and exceptionally cool
Peripheral boards from late 1990s and early 21st century motherboards often have small 12v fans and if you look closely you will see that they have their own lovely little heat-sinks over the fans. These little 12v fan heat-sinks are great for 20w DIY amps like the little amp I made last month from odds and ends
