http://www.bot-thoughts.com/2009/08/simple-diy-pcb-etching.html
Vinagor/peroxide/salt
muratic acid.
http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html
http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html#analysis_acid
http://www.solarbotics.net/library/techniques/buildpcb_trnsfr.html
Best Review:
http://www.mgchemicals.com/tech-support/instructional-guides/dry-film-resist-416dfr-instructions/