I just spent about a week cleaning up my workspace, which included harvesting parts from a number of devices.
R/C toys are pretty easy. Most abandoned RC toys do not have a remote. If you do have a remote, try it with other RC stuff, it might work. Keep the remotes - you never know when they may actually be useful. The RC device itself will yield motors, gears, axles and wheels if you want them. Keep an eye out for rechargeable batteries. Each RC toy will have a small circuit board in it which you should keep because it will have one or more H-bridge circuits in it which can be used to drive motors. Also the receiver chip can be used for communications if there is a paired remote. I have a robot with an RC receiver board in it for just this purpose. The plastic shell and other junk can be recycled. Sometimes the battery compartment is modular enough to dremel off and re-use.
Printers and scanners have tons of good parts in them. Motors, gears, sensors, cables, connectors, rods and optical parts. My favorite is the photo-interrupters. Most of the bulk of a printer or scanner is plastic and metal dross that can go in the recycle bin. What's left takes up a lot less room. Speakers can be useful so keep those intact. LCD displays are generally hard to re-use unless there is a driver chip for them, but LEDs and 7-segment displays are easy to re-use.
Buttons and switches also come in handy. I always keep the screws and other small hardware from a tear down.
Other devices that have good salvage in them: VCRs or DVD players, copiers, mice, fax machines, old motherboards and dead computers. Anything which does something interesting but no longer works is generally on my hit list. I recycle the metal and plastic, salvage the motors and gears and throw the PCBs into a box. Note that tossing circuit boards into the trash is not a good idea. Things that are not so good for salvaging are cell phones, hand-held video games, TVs and CRTs. They either have no good reusable parts, or they leave you with bulk dross that you can't throw away or recycle.
Things that can be salvaged from an old PCB are voltage regulators, power plugs, connectors, buttons, generic ICs, sensors, cables, resistor networks and jumpers. Most chips have identification on them, so you can look up the data sheet (if available) to see if it's worth keeping. For large-scale salvaging I recommend a heat gun or something similar which can melt off a lot of parts at once. Trying to desolder components from a motherboard is just too painful. Generally, surface mount components, large ASICs, unmarked chips and large connectors are too hard to get off and not worth the effort. Small parts like resistors and capacitors are also usually not worth the effort since new ones are so cheap.
Organizing the salvage is essential. Large ziploc freezer bags work fairly well: you can see what's in them, write on them and keep piles of them in boxes. Sometimes I create a salvage bag for a device with all the useful parts in it. Write useful information on the bag, like what kinds of battery or power supply the device used, or the exact model number. I also have bags for motors, gears, cables, wall warts, connectors, speakers and other large parts. Smaller parts can go into coffee cans or sandwich bags. I have a can of screws and nuts that I can search through when I need to replace or fix something.
Have fun disassembling!