I have been working on enabling CircleCI/GitLabCI in the sagemath repository. As one application, I am now playing with automatically setting up sage-binder-env branches from CI for every build. My idea is that this could allow people to include a "launch on binder" badge on trac tickets so that code changes can be tried out by reviewers without actually having to build the code.
Have you considered such an application? What do you think about it?