Sygic also has NavTeq maps which work but again low coverage (better than Ovi). TeleAtlas has better BG maps and fortunately Sygic supports them if you change the format in the config file, however the rest of the maps will stop working and you can only use them in shareware mode since TA maps are not sold for N900.

You can also try Mappero with Google Maps or Virtual Earth, you can download maps which you can use later.