I tried that one and no luck... I think the problem is that my hosting company has done some peculiar things at a higher level, which are causing a conflict in the rules I am trying to create.
To further complicate matters, I have recently re-branded a site, but still have to support some legacy URLs for existing customers. The old URLs are on a completely different domain. In fact, there are a few URLs in play.
The fundamental problem here is that this whole thing grew out of a programming project I did for fun, and was not planned in the way I would have preferred. So many reasons why this is a non-ideal solution....
Anyway... directory structure - this is where it gets insane.
Base path for all my stuff:
htdocs/ (this is where .htaccess is and is my "primary" documentroot"
pgallery/ (this supports the pgallery.davidmays.com url, which is enabled by default by my host's server config, as a subdomain.)
stuff/ (supports stuff.davidmays.com/pgallery/ url, also a subdomain controlled by my host's server config.)
symlink named easyimagehost, pointing to the "pgallery" folder one level up.
Now, here's my full set of current rewriting rules.