Yes, but why are you asking? Do you need something to put in them for you pc or just because you want to put something in them?
I just want to know what other things I could buy to put into them on my PC
I sometimes use them for storage of parts (cables, standoffs, screws, etc) provided the box doesn't impede air flow.
My uncle has a Pc-ez bake oven that goes in there. It can fit mini waffles or pancakes and they taste great. Don't know where he got it but I'm sure there are more out there. I have seen some people make cup holders out of them. The coolest thing I saw was a when someone made a stand for his tablet out of one and he could control the computer with his tablet by the click of a button.
drawers for little parts???? you don't HAVE to use them.
Fan controllers, optical drives, USB/SD card readers, 5.25" water cooling reservoirs, the drawer mentioned above, LED controls, hot swap HDD/SSD bays, fans, temperature readouts. Thats all that I'v seen them used for.