I just released Beta 1 of
RocketCake, the free responsive website editor. The internal beta test went pretty well, and I am happy that the testers loved that editor. If you just want to design a ready-to-go website without the need to code anything, it seems to be working very well for now:

You can
download the editor from its website, but keep in mind, it is still in Beta. No major bugs are known for now, and it seems to work well.
There isn't a Mac OS X version yet, but work has started for this already too.