Follow these instructions if you want to create a customer named app in Heroku:

http://myapp.herokuapp.com

over

http://tranquil-beach-9125.herokuapp.com

Note: This is different than mapping tranquil-beach-9125 to a real prod domain (i.e. nutshell.com).
To do that you must first create a named app, then point that to your prod domain.

http://myapp.herokuapp.com -> http://www.nutshell.com

Short version
> heroku apps:create myapp
> git remote rm heroku
> git remote add herkou git@heroku.com:myapp.git

heroku-named-app

Long version

Here’s how to create a named app in Heroku assuming you’ve already got one deployed on Heroku with a name like tranquil-beach-9125.

1. Create your named app.

> heroku apps:create myapp
Creating myapp… done, stack is cedar
http://myapp.herokuapp.com/ | git@heroku.com:myapp.git

To see your list of apps:

> heroku apps
myapp

2. Point the git remote ‘heroku’ to your newly named app.

> git remote -v
heroku git@heroku.com:tranquil-beach-9126.git (fetch)
heroku git@heroku.com:tranquil-beach-9126.git (push)
origin https://github.com/xxx/pss.git (fetch)
origin https://github.com/xxx/pss.git (push)

This shows where your git remote heroku is currently pointing (to that hard to remember name heroku created for you when you first created your app).

We are going to remove that git remote name, and then point it back to the newly created named instance we just created.

> git remote rm heroku
> git remote add herkou git@heroku.com:myapp.git

To add prod as a remote to this repos also go:
> git remote add prod git@heroku.com:myapp.git

Voila! We are done. When you now check your git remotes, you should now see heroku pointing to your nicely named repos with origin still pointing to your github instance..

> git remote -v
herkou git@heroku.com:myapp.git (fetch)
herkou git@heroku.com:myapp.git (push)
origin https://github.com/xxx/pss.git (fetch)
origin https://github.com/xxx/pss.git (push)

3. Test it.

To test make a change to your local repos and check it in. Then push to new repos.

> git push heroku
> heroku run rake db:migrate

This will push your repos to your newly created app.