If someone else has an answer to this, I'd love to hear it as well.
The best thing I've come up with so far is this:
Base web directory: /var/www/html
Virtual Domain 1: /var/www/html/domain1
Virtual Domain 2: /var/www/html/domain2
php doc_root = /var/www/html
Then, on the domains, issue calls such as: <img src="domain1/images/nude.jpg">
Not that elegant, but it seems to work fine.
-- Jason