it would be great if you would share how you did that, because there may be other cities and countries than NYC and the UK... ;)
so far i've only used google maps PDFs but that sucks. i've also had good experiences with offline Garmin maps based on OSM data, but that requires a GPS with much lower battery life than a ebook reader... a bunch of providers here: http://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin/Downloa...