Computer power cords aren't good for much of anything else, it would cost the same price to fab it into a 6' extension cord as a 12 ft extension cord. Though the wire gauge is usually pretty good.
The fans are good for many projects; I've made circulating fans for the tent, a cold smoker, a biltong and herb
dryer etc.
The platters from the hard drive make decent mirrors, wind chimes, signal devices. I mounted one to the back of my cell phone so I could view the back of computers, the flashlight illuminates the target and the platter mirrors the image back to me.
Magnets from the hard drives are useful for many projects.
Speakers can be handy for projects.
The wires from the power supply are a decent gauge and similar to that used in automotive applications.
The power supply it self can be used to generate 5 or 12 volt power (I suspect it would be a waste compared to other methods)
toroids can be used to create joule thief devices
Switches for power and reset are useful, the 120/220 power supply switch can take mains voltage.
CD/DVD drive motors can be used for assorted projects.
The laser from a cd/dvd might be useful if you're into that.
Many motherboard parts are useful for breadboard applications.
Speaker and microphone jacks are easy to
reuse for low voltage applications or audio
I've reused some of the plastic by softening it with acetone but I wasn't impressed with the results.
The metal pieces are pretty useful but they take a considerable effort to refabricate.
The clock battery and an
LED could make a flashlight of sorts
... those are the easy ones off the top of my head.