Another to add to the list of alternatives (this one has been serving me nicely as of late): http://middlemanapp.com / https://github.com/tdreyno/middleman
I like how Middleman handles layout templates, YAML front matter, dynamic pages and livereload. Dislike the idea of including Sprockets for asset management though, seems too much cruft for just prototyping. Suppose it makes sense if you want a tool that doubles as a static site generator.