i once came across a vittoria bottle cage toolkit lying in the gutter. stopped to pick it up and looked up the road to see if i could see anyone who'd dropped it. saw no-one (you can see a fair few miles down the a34 in manchester), so pocketed it and headed off, keeping an eye out for anyone coming the other way looking like they were retracing their route.
pondered what to do for the rest of the ride, deciding to post on here and see if anyone had lost one. got it home, and it had clearly been under several car wheels; all that was salvageable was a co2 cartridge. the rest, including a co2 pump, crank brothers multitool and other bits went in the bin