Have you tried some of the other aesthetic options? I use Spring, personally, though many love Dark, and a few like Ugly. I suggest playing around with some of them in your "Settings" page. I kind of like your grey header, though I think if you used it you would have to change the colour of the font on it for "feed,chatter, global, tags, community, badges"
Oh my god... I didn't even realize there were other themes, oops haha. I guess I should have looked through the site more before posting something like this. I'm currently using the spring theme which I think provides a bit better contrast. And yeah, I agree with you on the grey, looking at it again now it probably should be a few shades lighter. What do you think of the font size?
I definitely have to up the font size on Hubski, personally. Well, actually I just zoom in on Chrome.