Is there some underlying standard format for comments on the web? Otherwise Javascript-trn would have the problem that you can build it but they won't come. My uninformed impression is that there are scads of different web forum/comment software packages out there, and that they probably aren't very compatible. So j-trn would need some customization for each different web forum/comment package.

There is one web forum I am on where I am told there is a Firefox add-on that will let you killfile things on that forum software only, but I've never gotten motivated enough to find it and install it.

(Note: I probably have no idea what I am talking about here.)