The Atlantic, NY Times, Techcrunch, Extreme Tech, TheNextWeb, Github, bbc are the main ones off the top of my head.
Unless someone has already done it it, it would be very interesting to see the break down of front page stories by source and by poster.
I've seen this first hand: many of my blog posts are submitted to Hacker News shortly after I tweet them. Sometimes I know the submitter, and sometimes I have no idea who he/she is.
This of course is independent from what the article discusses. It's possible there are sites who make an effort to get hundreds of votes on HN but I doubt that's the case with TC, the NYTimes, etc.
- http://news.ycombinator.com/submitted?id=russellholly
- http://news.ycombinator.com/submitted?id=mrsebastian
- http://news.ycombinator.com/submitted?id=adeelarshad82 (their social media marketing manager, according to LinkedIn)
- http://news.ycombinator.com/submitted?id=11031a
Then there's the mystery of:
- Maxko87's (now hellbanned) autosubmitter for ExtremeTech: http://news.ycombinator.com/item?id=4441016
- evo_9 who heavily submits stories, about 50% of which are extremetech.com: http://news.ycombinator.com/submitted?id=evo_9
- ukdm who heavily submits stories, about 50% of which are geek.com: http://news.ycombinator.com/submitted?id=ukdm
TechCrunch I think is as simple as YC startups going there and then propping each other's articles up.
The Atlantic I'm not sure about, but they did just get busted spamming Reddit so I wouldn't be surprised.
GitHub probably has high double-digits overlapping users on a site like this, I doubt they need to do anything nefarious.
It would be fascinating to see who posts what.
Sometimes people only ever post from one source. Some people only post from a small selection of sources.
The list of sources you give is odd. Some of those have god quality content. Others, not so much.