You are able to see all workflows/jobs for a given branch by going to{org}/{project}/tree/{branch} such as
It would be extremely useful to see a list of all tagged jobs/workflows for all tags. We use tags to trigger staging/production builds and have no way of visualizing a record of all workflows/jobs of this type.
Added filtering to be able to get workflows that have done a certain step would also be very useful. For us, viewing all workflows that have succeeded job deploy-production would allow us to fully use Circle to manage deploys.