I bought one (probably not the exact one i linked) for mounting a UPS and a home security camera DVR unit (I don't buy into the security as a service from all of those options), but it never got installed. So the DVR/UPS just sit stacked on a shelf unprotected, but that's what the missus wanted. So now it's that thing that just sits there taking up space that is hard to sell at a garage sale, and I can't be bothered to create an ebay account to sell it.

Also, even if you don't have rack mount equipment, they make the shelves you can attach to the rack mounts and set other gear on them. So yeah, you can really clean some stuff up with these.