This was going to be a longer post but instead I turned it into a Github project.
https://github.com/hoitomt/sinatra_skeleton
I have another one with Grunt, Bower, Flight, Coffeescript, Sass, and RequireJs (also jQuery Mobile). This project doesn’t have any Ruby. It is built up into a project but you can strip out the jQuery Mobile stuff to get to the essence of the project. As a side note I started down the path of Gulp (too new) and Browserify (couldn’t cleanly integrate Flight and Flight was more important than Browserify). But I ended up coming back to RequireJs