i got a GPS fix in okinawa. the ovi maps app didnt have maps for that area built in.
i installed Maep and it pulled maps from openstreet when i was online (via wifi of course).

i will be in tokyo soon, will definitely need street maps (finding my way back to my hotel after a crazy night out, usually). gjiten and mscim are also invaluable with my child-like japanese skills.
even with the phone part being useless (for me without a SIM), the n900 is a fantastic companion in japan.
i took my 770 with me in 2006, my n810 in 2008, and now the n900. havent taken a laptop out of country since 2005 =]