Hey there! I've migrated from reddit and from what I've seen so far I think I would really like it if this became my main site. Everyone here seems really thoughtful and nice so far, so I thought I would at least give my opinion of what I think of the site layout so that it might be better in the future :)
The first thing I notices was that the body font was very small. This make it a lot harder, for me at least, to read through long posts without straining my eyes. If you look at other text dominated sites (for example, the New York Times and other newspaper sites), they have all increased their font size to around 14px or 16px to alleviate this problem. Also, because of the large amount of white space on Hubski, I don't think this would have any negative effects on usability.
For an example of this, the post title font size and author font size on the feed only differed by 1px (13px and 12px). I changed the the title to 16px which I think was a significant improvement.
I also changed the color of the header to a light grey which helps dictate the flow of the page, helping the user to more quickly distinguish between the static menu of the site and its content. I also changed the a:visited attribute to a lighter color so it is easier to tell when links have been visited.
That's all I got for now, but if this gets a good response I would be happy to keep suggesting things!