Holistic view of stories and team velocity

I'd like to see a holistic view of stories and "team velocity" across several projects. We are a small consultancy and we often find ourselves working on several projects at a time (which, I know, isn't necessarily ideal, but that's the way the work turns up). It would be useful -- to me -- to have an overall "uberproject" where I can line up a balance of stories for all our customers in some order, and see the team's velocity across all projects.