Great discussion, I'm far from the master mechanic level that many MSTA members are but I do carry a decent took kit (an old leather fanny pack works good for me). One thing a friend recommended I carry is the socket for removing the bold on my Triumph Sprint ST, its a huge one at close to 2" and something I may need if I have to remove the wheel.
I like the suggestion about riding with people with tools, and since I'm not good at using them I like to ride with others who are
I also have a big bag of "stuff" for various issues like flats (including a compressor), syphon for gas, rags, cleaners, WD-40, chain wax and many more items. I've told people "I carry this stuff in case, not just for me but others I ride with." One time on an Ohio lunch ride I was on my VFR and didn't want to use my soft bag to carry all my stuff, so I left it at home. Sure enough I got a flat on the ride home, luckily the other 2 riders had flat repair kids and we were able to get it patched. This bag is alway in the top case of whatever bike I'm riding these days.
One of my rules is "if I use something I carry, I replace it with the same plus an extra." Zip ties are great in a pinch to replace a lost bolt. Buf of course the blue book and cell phone can be the ultimate tool.