There have been several Instructables about recycling electronic components.
However, you can also recycle whole sub-systems. The easiest to recycle are power supplies. You usually find them where a coil, a diode, and a capacitor are close together. See the bottom left-hand corner in the picture of a cable modem. (With the red border in the PDF).
These systems are designed by professionals and should also fulfil EMC and stability requirements.
Step 1: Identify and Separate
Measure which voltages are where before recycling. Usually 5.0, 3.3 and 1.8 Volt.
Cut out the interesting parts with a hacksaw.
The picture shows a few of the recycled supplies and an RS-232 buffer in the bottom right-hand corner.