In the spirit of finding a use for something which would otherwise be thrown away, I made a set of S-Hooks from plastic hangers (the type that you get from department stores when you buy pants). These hooks can be used for medium-low strength applications, for example, I use them to hang half of my mugs. This project is relatively simple, and the method could easily be adapted to use different tools. I will describe how I made mine.

Things you will need:
-Plastic pant hangers
-2 Strong Pliers
-Hammer
-Table Vise

Step 1: Smash Hangers

In order to get the metal part, you must separate the plastic hanger body from the metal hook. This is pretty simple and could be done a few ways, but my favorite way was to simply smash the hangers with a hammer. One hard hit, placed right over the intersection of clear plastic and metal hook, was enough for most hangers, though some needed a bit more convincing.

Step 2: Bend the Hook

Now we bend the hook into the S shape that we're looking for. First you'll want to break off the threaded part of the hook. The joint where it is attached is weaker than the rest of the hook, so you can just bend it back and forth to break it off. Other methods, like a hacksaw, may be more effective, but using pliers worked well enough for me.
Using two pliers helps you isolate part of the hook and bend the rest. Bend the straight end of the hook back in the opposite direction of the existing curve. The shape/size of the bend made depends on your use of them, I was planning on attaching mine to a wire grid, so I wanted a small curve on one side.

Step 3: Test and Repeat

Now hang your hooks on some rack and see if they hang right and hold what you want them to. It's helpful to actually hang something in them to make sure the hook won't tilt and let the hung object slip off. Reshape as necessary, and repeat until you have as many hooks as you want!