So it turns out Moodle is a pretty popular platform for spam. On open sites that allow anyone to register, you can create a profile, fill it with links to other sites (this is ‘good’ for SEO), and then spam the profile address to blogs, improving the link-juice of the profile page, and in kind, improving the link-juice of the sites on the profile page.
How did I find this out? Someone has started linking to a Spanish university’s Moodle profile in comments on my blog. I knew it was spam because I had a dozen or so other comments from other IP addresses, email addresses and user names, all with the same content, but a different URL each time.
This is the first time I’ve seen Moodle used as a spam-link clearing house. Certainly won’t be the last.