Ha, I was amused to find that a sci-fi story had the same idea I’ve had, about spam filters eventually being a source of artificial consciousness:
“AOL is the origin of intelligence?” She laughed, and
he couldn’t tell if she thought he was funny or stupid.
…“Spam-filters, actually…”
— Cory Doctorow, “I, Row-Boat”
Great story, by the way. And free for download, thanks to Doctorow’s enlightened attitude about sharing-as-marketing.