rake -Tgives you some but not all of the tasks that are available. If you are only a part-time user of Rails, it's easy to forget the precise syntax for those undocumented commands.
That's why I really liked the TutorialsPoint page which lists many more of the built-in rake -T commands. Very helpful.
Now, if folks would just fully document their rake tasks, we could see everything right where we need it without resorting to an external site.