Since this has just been resurrected I was jut pondering on my kit, other people's kit, and my experience on the road of what myself and others have actually needed. I do carry a fair few bits and bobs with me since I'm pretty self sufficient fettling wise these days. I often stop to help others when they haven't got something they need. Things I carry that have helped other riders over the past 3 years are:
Zip ties and/or insulating tape. Amazing what you can fix with these
Broken mudguards are my most common reason for providing these to people.
A decent pump. I can't believe how often my question 'are you ok?' to the fairy-visited results in a 'have you got a decent pump?'. The pressure my Lezyne Road Drive can achieve even with just me pumping it is a source of surprise. If I CBA then I just use a CO2 cartridge on them.
M5 bolts. It's amazing how often people's rack bolts fall out.
Chain tool and 10 speed quick links. Seems many people are not geared up for a chain breakage, and even more surprising how a few don't know how to use a chain tool
Tyre boots.
Latex gloves or if too late for that baby wipes
Spare tubes. Some don't seem to think of worst case scenario and take just patches, or one tube and patches, which doesn't help much when you get a pinch flat after changing the tube the first time.
Valve extender for deep section rims. People might find this hilarious because I don't Audax on a bike with deep section rims, but I carry one because I've twice given one to a rider who ran out of long valve tubes, couldn't get any more and was about to pack because if it.