A "production version" of Rawnalyze, a free program for the detailed analysis of raw images is available. It is not a raw converter, rather it helps understanding raw issues and analyzing actual images. Its user's guide can be seen as a raw primer.
The native raw files from all current Canon cameras and from many Nikons and some more are accepted, while other cameras' raw images have to be converted in DNG (Adobe's DNG converter is free). No Mac version is available, sorry.
See http://www.cryptobola.com/photobola/rawnalyze.htm