In the latest sprint, Microsoft released a very nice feature for reporting purposes: Charts for Work Item Queries.
It is incredibly easy to use. You do not need anything but Team Foundation Service. You can click on the link while opening a WIQL query:
and creating a new Chart
Unfortunately at the moment is just supports flat lists, but in the future it is going to support the two other WIQL resultsets. It is very handy, you can embed it into an email or whatever, and it comes working with no configuration. Well done team!