The above knots are the most important to practice for rescue work. Knots and splicing is a vast body of work with lots of neat applications. Before cam straps were prevalent, most of us used a Trucker's Hitch to safely secure our boats. Improvising a seat and chest harness may prove useful for safely lowering a rescue person. The Grog site also shows a simple hasty harness tie. I highly recommend bookmarking the "Animated Knots by Grog" site - especially the Grog Search & Rescue for future reference.