We added some drag and drop functionality into the custom dashboards starting WAY back in version 5.0, but I just found some cool new functionality with the drag and drop capabilities that I thought I'd share.
For this exercise you'll need a custom dashboard with a usage pane (scoped to whatever your favorite group is) and an entity trend.
I chose my SQL VMs group here.
After that in order to populate the Entity Trend pane all you need to do is drag the VM from the Usage over to the graph. You can easily update these on the fly. Which in my opinion is pretty cool.