Am 21.07.2012 02:59, schrieb Knud Sørensen:

We might use a challenge -response system for spam protection.
It could be that you have to download, compile and run a small d program
to get a key for posting a comment.
Due to the nature of the site I think it could be okey.

Interesting idea ;) In fact, it could really work in this case..

Another possibility is to look at Vladimir Panteleev's DFeed and see
what he uses, he has integrated a number of anti-spam services there: