First Aid kit multi-tool pump zip ties, various sizes electrical tape duct tape emergency blanket (the thin, aluminum foil type) ball pen lighter pocket knife Cliff Bar energy drink Spot Emergency Satellite locator GPS spare riding jersey water thin, light rope; 8'
sounds like a lot, but it's not bad. the rope I carry since I was out riding and my bro broke his knee, we couldn't find anything to tow him out of the bush, a rope would have saved us some trouble as he was able to sit on his bike. the spot locator is a great device for sending messages to 911 or friends. I mostly ride in areas without cell coverage and very view riders, if something happens this could safe my life. a couple of Cliff bars are always good, even if its just a short ride, zip ties, black tape and duct tape are handy for emergency repairs. the rest is pretty straight forward...
1 tube, 1 tire levers, 1 pump, allen keys for my axles, cell phone. if anything else goes wrong and you can't fix it yourself your gonna end up walking most likely any way. depends how/what/where you ride. I just ride bike park type stuff so i can pack light because everything else is fairly close.
Camelback with 4L of water at all times Metric 10 piece folding keys Cell Phone First Aid Kit One-hand fireman Swiss Army knife Zippo Lighter Hand warmers (since they are little pouches that warm up they might be useful for other things than just hands) Nutrigrain bars/granola bars and sometimes chocolate bar or some candy.
1.5 litres of water; Topeak multi-tool Smal pump Air chamber Glueless patches Two tire levers Some zip-ties Wallet Mobile Phone A Tissue A jockey wheel, bolts, brake pad...