For epub files from the meta information:
Code:
<meta content="Project Gutenberg EPUB-Maker v0.02 by Marcello Perathoner <webmaster@gutenberg.org>" name="generator"/>
I've not found them that useful in trying to do clean up to a nice epub format. Usually the same mistakes to be found in the raw text are still there, the format is sort of funky, and sometimes additional errors have been added. That and like all automatic generators a lot of unnecessary tags are added that are just a pain to go through and remove. But if you are just looking for a epub version to load onto your reader, it is a good source.