From the Entourage store, this free app, "HYReader," will read html files (along with chm/txt/umd):

http://www.entourageedge.com/apps/e-books.html

(I can't give you the download link because I'm posting from home, where I only have dialup and am using my desktop system. Entourage will not provide the link unless you're connected with their device.)

HyReader works very well: you can enlarge or reduce the font, and rotate. You can't do that with the ES File Explorer, I've discovered. HyReader will even work with embedded links, like a regular web browser. Nice.

Just wondering why, though, clicking on an html file won't automatically call up the native browser? A glitch perhaps? Or maybe the browser doesn't have permission to access any files on the device.