There are many complaints about how difficult it is to use the epubcheck validation tools.
I have made a very small tool for Windows (actually a two line batchfile!) to make it as easy as drag-and-drop. I enclose a zipped file containing the tool.
It contains epubcheck-HOWTO.txt, containing an annotated how-to-use edition of the batchfile, and epubcheck.bat, which is the "clean" twoliner.
Of course you must have some version of java on your machine, as the epubcheck validation tools is a java programme.
I am sure this can be done in a similar way (python, shell script, whatever) on a mac or linux box - if anybody do it, or improve my little twoliner, please share!