Ubuntu/Unity?
edit: a google search of unity doesn't show it with a menu bar for file, edit etc anchored top the top of the screen like OS X, those menus are still in the application window.
I'm an Enlightenment user when not at work, so maybe I need to create a E19 fork (I wouldn't know where to start).
About your edit. Are you sure? They are not in application window for me.
There are also some nice alternative icon sets, like the Numix icons. Overall, I really like Unity now compared to when I first tried it a few years ago, and I'd rather use it than Windows 7 or 8. But it probably does need a couple of tweaks to fit your needs.