Bosca Ceoil is made to be an easy to use tool for creating music loops. It is made by Terry Cavanagh, who, of it, said:
I made this because I find other music programs really confusing and distracting. Too many panels, buttons and knobs! I wanted something really simple, something designed to work the way I tend to create stuff – a process that I suppose I could best describe as: make something super simple, and keep tweaking it until it starts to get good.
There are versions for Mac, PC, and Linux. They all require Adobe Air.