ive seen something like that cant recall the name but loop rope round your back and then up through your legs and descend, sure wayland posted about it also.
its a non mechanical form of abseilling, and not only does it hurt, a lot! but its dangerous as wotsit thingy majig
unless you are experienced and have harnesses and a figure of 8 or similar descending device, dont abseil down, you will die
also, if you need a rope to get down safely, you will need one to get out safely, its a multipitch climb at least, belaying whilst pegged to a shear face is an interesting experience to say the least! lol and even if not vertical but still needing ropes, youll want a harness and know good prusiking technique.
if a route needs roping, make sure you have someone experienced "showing you the ropes"
sorry to be dramatic, but ive seen people hit the deck from relatively low single pitch sport routes, it hurts them and frightens the hell out of everyone else, as well as spoiling the onlookers day by first aiding the victim/dimebar and carrying them out to ambulances