Or little computing tricks and hacks
After having added a few apps in heroku, I could not tell which one was what. Although the random names give by the server are great, I needed better naming conventions.
The site allows quite easily to rename you app… except that when you want to git push or heroku open the app is of course, not found.
Thanks to stackoverflow, I fixed the problem:
git remote rm heroku
git remote add heroku email@example.com:yourappname.git
There are other methods mentioned in this page, but one of them did not seem to work.