Drilldown on a particular Team Project Collection
Identity service, listing the users in each of the TPC UserGroup
Team Projects, names, state and uri.
Build Service, listing all builds, with fail ratio and type of build (please wait, the build service is dead slow to give any information of interest)
Build Machines, ordered by Project, with activity status, and RDP links, so as to access these easily.
The killer feature is to get the host names of the controllers and agents, which is to my knowledge impossible to do with the standard tools.