I have an idea for project I'd like to develop, but I don't have a domain registered for it yet. Is it possible for me to register a project and work on it locally with my own web server until it is a little further developed?
I did not have any problems working on a project locally. The oauth authorization screen may complain about an unverified host until you can confirm your domain, however. When setting up the project, just use a domain you plan on using in the future. If you don't know for sure, you can always setup a new project with a different domain and just switch the keys out in your config settings.