Handcuff key- Never know when it might come in handy.
A spare truck key- I've got a hide-a-key on my truck, as well as remote unlocking via phone, but I also keep a spare key one my person. It has come in handy on a few occasions.
Lockpicks -(This one you really have to be careful with legally.) It takes a lot of practice and it isn't foolproof, but they can be useful.
Sometimes a
Flask of Wild Turkey Rare Breed- 108.2 Proof means it will readily light on fire if kept at room temperature or above, it can work as an antiseptic (Typical 80 proof alcohol actually doesn't work well as an antiseptic), and it's still drinkable....unlike, say, Bacardi 151.
Permanent Match- Great little fire starting device. Like a zippo it can use just about any fluid that will burn. However, unlike a zippo, the fluid doesn't evaporate in a week or two.
Steel Guitar string- This stuff can be pretty useful when combined with a multitool.
A CPR mask- I used to carry one on my keychain. I don't anymore as my CPR certification expired long ago and I haven't kept current on technique. I really should take the course again.
Nitrile Gloves- I kept these with the CPR mask and actually used them more. Great when you don't want to touch something gross or need a little hand protection. Latex free as well.
Ear Plugs- Great to have on hand any time you are exposed to loud noises.