Add Open Street Map as a layer
Allow Open STreet map as a layer for non NZ locations
I'm looking to add more options for sharing via urls, maybe including transparency & other map type to show (satellite imagery, street map, etc.), in which case you should be able to use this as a hack to achieve what you want.
However, I won't be showing the street map layer by default as most people only ever use the topo map layer on its own, so inefficient to load another by default that is more rarely used.