Thank you insaneike...
Yes, pretty much everything here is crawled by Google. The obvious fix would be to secure download links (they would be uploaded as attachments) so that only approved forum members can open them - except in designated free for all sections. This would allow one to both restrict downloads and to see who has downloaded what. That's how it was done at now deceased sites such as ewef.net.
Posting open links that anyone and everyone can download is just plain dumb. :hammer: