Ask HN: Any good open source rails apps to learn from?

https://github.com/diaspora/diaspora for example. diaspora is also using backbone.js for some front-end stuff, which is quite interesting to have a look at.

also, check out http://railsapps.github.com/rails-examples-tutorials.html

I haven't looked at it in a while but Redmine and its fork Cool Project might be worth a look.