I'd like to propose the ability to submit callback URL's. I banged this up in a few mins but it's pretty ugly. The change is in oauth2/init.py but should bubble up so that it's easier for the integrating app to specify.
Support callback URL
+1 Would be really nice to get this in there.
Also the attached pull request is not (and is probably not intended to be) a valid solution. It simply hardcodes the callback http://localhost:8080/haha.