reference data wishlist

My idea would be to collect here reference data that we may want to provide (via cvmfs or through a local DM run) that are currently not included in cvmfs. My hope would be that from this list we may be able to determine shortcomings of proposed repository/directory/metadata structures.
@natefoo feel free to close this if you think it's not interesting, or if there's a better way to build such a list.