eXe is an open source content authoring tool which works on both PCs and Macs. It has been developed in New Zealand and is free to download. It's reasonably straight forward to use and there are some helpful screencasts on the site which give you an overview of how to use the tool.
"Participation in a comprehensive ex vivo training curriculum for laparoscopic colorectal surgery results in improved technical knowledge and improved performance in the operating room compared with conventional residency training"