Camera Belt Clip mounts, also referred to as "backpack clips" or "hat clips", can be used in many ways.
As a belt clip, they are great for filming in public areas (such as busy streets like walking down Bourbon Street in New Orleans) without drawing any attention to you or your camera.
You can also attach them to the strap of your backpack or your baseball cap.
Other ways you might not have considered using them -- clipped on to your curtains for a full room view; or clipped to the front of your toddlers shirt. Any thin, relatively solid location can become a temporary but secure action camera mount when you use the clip-on clip.
There are also super heavy-duty clips that also include trip mounts usable for action cameras as well as full-size video camcorders. They typically are overkill for action cameras due to the light weight, but still work great and usually have a bigger grip or "mouth" allowing your clip on to something wider.