Do you recognize these cool / cheap) little items

This is a can opener.  I used to always carry one of these on my key chain (or dog-tags.) One of these was included in every pack of C-rations.   It weighs about as much as a Kleenex and it's about an inch long or so.  It's a handy little tool.  You can use it for prying open paint can lids or as a screwdriver or cutting string etc ... I really miss having one so I started looking on the web to see if I could buy one.  Do a search for "P 38 can opener" and you can find a million of them for sale.

Also, I know it LOOKS like it would take forever to open a can with one of these but that's not true. You can open a can in no time flat. Of course, I was probably really hungry if I was opening C-rations. No, just kidding, I opened lots of non C-ration stuff with this thing.

How about the one below?  It's a magnesium fire starter.  You can buy one for less than $5 here (Or search the web for "magnesium fire starter."  This one comes with a little hacksaw blade you can use for scraping.

Here's a review.  I was glad to learn about the cotton balls smeared with petroleum jelly.

Magnesium lights up at roughly 1000 F, so this will start a fire on the first attempt if you've got the shavings in a nice little pile amongst some kindling. If you mess it up, no problem; you've still got a few hundred chances worth more of magnesium to fumble with. This is also a product that's been on the market likely longer than you've been alive, so don't think you got the last one they'll ever make.

With this, you just take your knife (the back works as well as the blade really) scrap off some magnesium in a little pile, put your little wads of bark or other hairy kindling (or pine cones, bits of cloth, or whatever you can scrap up as you can anywhere) along with your regular kindling, strike the flint side of the fire starter with the back of your blade or anything made of steel, and make sure to look away when it starts because the light is bright white like a halogen lamp on full.

If I had to compare it to anything, it's like setting off a flare.

The sparks from the magenesium catching fire don't go flying, so no worries about one shooting up into your face, but also don't be under the impression that you or your friend can hold the magesium and kindling while shooting sparks at it so that you can immediately blow on it. When it lights, it lights instantly, and it's so hot that it will burn right through to the bone if you light it on skin. If you've ever seen sugar on fire, this is far more serious, but it's safe so long as you don't do anything stupid.

It is meant as a backup survival option to matches/lighter (which are your normal means for firestarting). Also carry good tinder (I like cotton mushed with vaseline - cheap and effective).

Bottom Line: It's so small it can go on your keychain or be thrown in your backpack as one of those things you always have just in case, but forget about until you really need it. Its of negligible weight for you weight weenies out there. And it's so just plain cool that you'll find yourself using it not just for that moment when you're in trouble and panicking about the fact that everything they taught you in Boy Scouts was entirely wrong, but when you're 'out there' and there's absolutely nothing wrong.

If nothing else, it's a neat bit of science (kids go crazy for this stuff) that just might end up saving your caboose some day. It's small, cheap, light, and effective--which is something we can rarely say about anything truly useful these days.