Packing multi use items is one of the corner stones of the ultralight backpacking philosophy, but this is by no means a new phenomena. One of my favorite historic examples of this idea is Rice's Half Shelter Tent designed by Lieutenant-Colonel Edmund Rice, a U.S. Army officer and Civil War veteran, in 1896. His shelter was carried by two soldiers; who had one identical half each.
When put together it formed a two person tent and when dismantled it could be worn as a cape by each soldier, or in fair weather it could be rolled into a knapsack for the soldiers blanket using the new 'guy line strap'. Genius. I love it for its simplicity, functionality and robustness. All the things that good kit should be.
Rice was quite the inventor also developing his Trowel Bayonet, another great multi use item.