Some way of grouping things by canonical links would be neat.
Like if HN and lobste.rs (or other link aggregators) both point to a recent news story, then the fact that you've read the url they link to, should be a seperate concept from whether you've 'read' the discussion that points to the link.
And if you seperately have a feed of the originating news site, reading it there would mark it in both places.
This doesn't help if you follow, eg. five different news sites and they all report on the same event with largely the same facts (or even the exact same article copy syndicated)
Like if HN and lobste.rs (or other link aggregators) both point to a recent news story, then the fact that you've read the url they link to, should be a seperate concept from whether you've 'read' the discussion that points to the link.
And if you seperately have a feed of the originating news site, reading it there would mark it in both places.