I think I've turned the corner on my recent rant on spam. Somewhere I ran across a post that said that they had blocked this new "image" spam from their Gmail by using a filter to look for "multipart/related" in the message.
I went over to K9, right-clicked on an e-mail in the "Recent Emails" tab, and went down to Blacklist/Header... and entered "multipart/related".
This works pretty good. This morning, I got 29 spams and 25 of them were caught by this Blacklist entry.