I was using Firefox 14 as well as the latest version of Chrome.
As of this morning I am able to create and edit apps. The app that I created is using the same name that I attempted to create yesterday so I know that the issue is not duplicate names.
@dpwilson Yesterday one of the servers failed which caused app/group creation to fail. It was going very slowly, rather than not working at all, so we didn't notice until the evening. I fixed it last night.
The next release is built on all new infrastructure, which is much more resilient to failures like these.