Do you know an app to make easily virtual hosts on mac (I want myapp.local instead of localhost:9000) without playing around with apache?

Change your host files (sudo nano /etc/hosts) and add: myapp.local

Should be accessible inside of your browser at myapp.local:9000

Also, ngrok as mentioned by Swizec is cool but it generates its own url and not myapp.local.
ngrok is cool for testing on multiple devices no matter where they are. setup ngrok and forward the link to my brother on Windows for IE and my other one running Linux for whatever otherside of the planet. Pretty dope.

And a cool service to mention in this context is if you need a dns routing for certain hosts to specific ip addresses

I tend to use for subdomain testing so I can do something like which just forwards to localhost. (… )

I also use the ghost Rubygem to manage my /etc/hosts file.