The Item and Host navigators are great for dynamically swapping out the host or single items in graphs. 

Swapping out thew entire Host Group (or Host Pattern for that matter) would allow things like viewing the CPU usage graph on all your Productions servers, and then changing it to view Developments servers instead. 

The existing widget broadcasting/listening structure is pretty close to providing this feature. It 'just' needs a Host Group Navigator and widgets supporting Override Host needs to support host groups.

Attached is a screenshot showing two graphs that can be combined into one using the above.

(a stretch goal would be Host Tag Navigator and Item Tag Navigator, allowing additional flexible ways to change graph host and items)