I think that MT-Blacklist (and the various other blacklist implementations) should share 2 lists. The first list is the current lists we’re all sharing, a list of domain names that cause a comment to be flagged as spam.

The second list would be a list of carefully qualified domains of repeat offenders. This list would be a list of domains to request files from repeatedly as suggested on /. recently, a distributed “stress test” if you will.