Rails girls is a group dedicated to training up the next generation of Rails developers... who happen to be women.
They tend to run over a weekend and get women of all backgrounds (but without rails experience) to build a rails app from scratch.
They have a set of materials that is brief, but quite impressive - and if you follow them through step-by-step it's a quick tutorial on how to get a pretty decently functional Rails app off the ground.
Then follow the set of guides (links are at the bottom of the app-tutorial page) to get it up on heroku, to add authentication with devise, to use geocoding to add your widgets to a map, to create thumbnails for your uploaded images and more.
With just the above you can get a fairly decent rails app built for most purposes in a day or so.