I am using this post to collect together some information about digital signage. I will include references to resources.
I am considering the JW Image Rotator (free) and building a PHP backend to do an automated xml of a folder if images. Maybe someday write something more custom. @ckehayias wrote something similar in .Net.
@srushik – http://getcu3er.com/ ($50) with custom built ASP backend that builds xml from images.
@dszp pointed to @crewNeckTech mentioning http://www.drmretriever.com/ (not sure of cost).
@granata http://www.getsignboard.com/
Also from @granata (here) there is http://mediasignage.com and their free product.
More work and info to come
There is a technology tab on this site and the add content weekly so keep on the look out for your topic http://voiceofministry.org/.