This is not exactly woodworking, so I wasn't sure which sub-forum to put it in.
Magnets are cool, and fun, and very useful around the home and shop. Lots of us use rare earth magnets in many projects.
I have magnets in my featherboards. I use magnets when changing my DC bag to help hold things in place. We use magnets to hold notes to the door, and so on and so on...
What you may not know, is that computer hard drives (aka: hard disks, or HDs) contain two powerful magnets.
Here is a quick and simple photo essay on destroying old HDs to salvage the magnets in them.
Start with an old or broken HD that is destined for the recycling bin.
I am fortunate in that I work at a university and have access to a whole bunch of old HD's that are being scrapped and tossed into the recycling bin. These are 10+ year old units, either too old, too broken, or too small for continued use.
Peel back all the stickers, and then remove all the torx screws. There are TEN holding this HD closed. They really don't want you getting in there. (And of course normally you don't want to get in there, they are sealed to protect your data!!!) Actually 11, there was another one, even smaller than my smallest torx head screwdriver that I had access to:
Fortunately, a bit of brute force prying was enough to rip off the cover. Go ahead and force it. You don't care about this drive anymore, otherwise you would't be taking it apart! There may be a thin bead of silicone (or similar) as a sealant around the edges of the lid holding it down. Hopefully on your drive you won't have to get sou forceful, if you can manage to remove all the screws.
And here is my sample HD with both magnets removed. The read/write arm gets a bit bent. That really can't be helped, as it is most definitely in the way. But it's also very delicate, so it's easy to force out of the way. The upper magnet is on the left. It nicely has 3 mounting holes, that you can use to fasten it to something. The lower magnet is on the right. These always have some form of bent "legs" (for lack of a better term) sticking up. This makes them a bit harder to work with, if you want to incorporate this magnet into another project. Oh well, that's what hacksaws and grinders are good at removing!
Here I made a simple hook with some oak and a peg as a proof of concept, using the top magnet.
It's quite strong. I'm trying to figure out how I could use something like this in a featherboard in the shop. The trick might be the removing of the magnet once it is attached to the cast iron! Not sure if I could replicate those dial-magnets that are on a lot of commercial featherboards
And here is the lower magnet, just hanging on the body of my bandsaw. Note that the magnet isn't actually touching! The shaped legs are holding the magnet at almost 1/4" from the metal of the Bandsaw, and yet it is still strong enough to hold. These particular model of HD's have VERY strong magnets.
Got some more photos on my website, http://www.wordsnwood.com/2013/magnets/, but this is the basic idea.
Hope you found it interesting.