Inside computer hard-drives are one or two super-powerful magnets. Probably worth a couple dollars, potentially useful, or just fun to have. Inside the hard-drive, the magnets are usually glued to metal brackets that have holes in them. You can put screws through these holes to attach the brackets to a wall, and then you’ve got a wall mount for any metal object, such as a tool, that you want to keep handy.
You can find instructions online that tell you how to take apart a hard-drive. It’s easiest if you have a set of Torx screwdrivers. Helpful hint: hard-drive manufacturers often hide some of the screws under labels or in other hard-to-find locations. Getting the magnets out of a computer hard-drive is a fun project to do with a kid. I used the magnets I recovered from an old computer to hold a cover over the hole I cut into the front of my washing machine.