Brought us up to the newest Rules Emporium SpamAssassin rulesets. There's some pretty wily stuff in here. Check this out:
((HTML_IMAGE_ONLY_02 + MIME_HTML_ONLY + MIME_HTML_ONLY_MULTI) > 1)
describe FVGT_combo_IMAGEONLY1 FVGT - Image only type spam?
score FVGT_combo_IMAGEONLY1 4.3
This is a "combo rule" that (just like a Tony Hawk combo) gives a spam an additional 4.3-point bonus if all three of the standard "image only" type rules have already been matched. I think they just added this "meta" capability recently, and it's a great idea because it should help to put marginal spams over the top.
UPDATE: However, some of the new rules seem to be a bit