If you’re someone using Ruby on Rails, I strongly recommend you go and clone the Real World Rails repo on GitHub. It’s a collection of full Rails apps that are open source which you can read the code for and see how different people are doing things.
Quickly looking at the list, a couple of notable apps are Feedbin and the official Git website.
While I still consider myself an iOS and Mac developer first, I’ve had a ton of fun with Rails, which seems to have had a real resurgence in the last couple years. I’d tried other web frameworks in the past, but none of them ever stuck for me. Knowing Objective-C so well and having familiarity with Smalltalk, Ruby came really naturally to me, and the framework makes doing normal things incredibly easy.