things that are actually useful and will not get thrown away
1) key chain lights with replaceable batteries that don't totally suck. Even a coin cell and LED is actually quite useful and having extra flashlights around in a pen drawer or something can save the day. Make sure its not a shitty one that requires a stack of alkaline cells with dodgy contacts, a single lithium coin cell one with solid contacts is nice. Provide it with a silver cell if its a button cell kind so it does not leak if you want it remembered.
2) durable carabiner (metal), but they have to have a good spring. Useful for home organization (keep in kitchen drawer). Too many of these will just fail because the spring mechanism sucks and its just a disappointment. (niteize is OK)
3) miniature screw drivers that are not total shit, again useful to keep around in random places where you normally don't want to buy one, but it has to be made properly (proper materials, not one that deforms)
4) little pry bar or something (proper materials)
5) magnetic objects
6) miniature pen that will go in a place where a normal pen does not fit
7) miniature pocket knife (like the one that you open with a finger nail but its not too tight and its lubricated but not one of the ones that is like a box cutter that will open in your pocket)
solid plastic cards that are useful for scraping
9) well constructed minature boxes with good hinges and stuff, like altoids tins.. alot of people will keep them around for projects or accessories storage etc.
10) metal key chain stuff (be it wire rope, or metal), with a good ring, and as small a label/brand as possible, because that part is basically useless.
11) good miniature tweezers with case/sheath
Stuff that makes your car, remote places (shed, patio, etc) suck less