There hasn't been a CodeRunner question repository until now, but I've just created a "course" called C Question Repository and I've uploaded a subset of CodeRunner questions from the C programming course I teach into the Question Bank for that course. I don't guarantee they all work (some are very old and CodeRunner has changed) and some are probably inappropriate for use outside my own labs. Use at your own risk :)
I don't wish the question repositories to be visible to students doing my courses, so I'm going to restrict access to these courses to teachers who email me (email@example.com) with some evidence of the fact they're a teacher (e.g. a link to their Institution website) including a way for me to verify that the email address is theirs. Would you mind doing that, please? Once you're set up, you should be able to access the course and its questions via the Courses link in the Navigation menu.
I'd be delighted if in turn you would upload your questions to the C Repository course, putting them in a new top-level question category of your own.
I have been intending to set up a question repository for some time. I had a student lay the groundwork for a special stand-alone question repository server, but the project never really got off the ground. The approach I've taken now isn't too great, as it doesn't scale well and could potentially be seriously abused, but it's a start. We'll see what happens.
Thanks for the suggestion.