The disk of returning was used back in early in Runescape1 to get out of the "Black Hole Experience". The black hole was the place where people went when they got banned, but if you weren't banned you could purchase a "disk of returning" for about 10gp from a dwarf in the Dwarven mines and you could visit people in the black hole. When you wanted to get out you would just spin the disk. Disks are no longer available since the black hole was taken out in 2002.