If you jump between multiple Rails projects frequently, you probably get annoyed shutting down servers and starting them up again, and shutting them down, and starting them up again.
You start your Rails server like so (as I'm sure you know):
$ bundle exec rails s
That makes your application available at http://localhost:3000.
Additionally, you can run another Rails server from another project on a different port by passing it the
-p argument. Let's say we want to start the server on port 3001.
$ bundle exec rails s -p 3001
Now this application is available at http://localhost:3001.
Alternatively, check out Pow. I love the concept of it, but I ran into too many issues and just went back to the old-school, command line approach.