We volunteered with our local Scout troupe as bag-sorters for the City to Surf "fun run" today. Before the race, the runners each put their personal effects in a plastic bag with their registration number on it. These bags are (roughly) colour-coded into groups of 10,000 or so (there are ~70,000 runners in total), and then trucked to the finishing line at Bondi Beach, 14km away. At Bondi, we unloaded them from the trucks, and then sorted into groups of 1000, and then rows of 100. Our little group of four (plus two 8-yr olds) was responsible for around 2000 bags (numbers 13,000 - 15,000). At the end of the race, the runners front up to the collection area, and we have to find their bag by their bib number.
What you see here is a pile of bags just unloaded from a truck, and a sea of (mostly) green, sorted bags ready for collection.
Oddly, it was a heap of fun. Most runners were genuinely pleased at how quickly we got their belongings back to them. This may have been because they'd seen the total chaos across the way with bags 30,000 - 40,000.