MS makes the maps for MS Pocket Streets that cover the world freely available for download (Download details: Pocket Streets 2005 Downloadable Maps. I believe they are free now because they stopped developing Pocket Streets with 2005 being the last version of it.

Does anyone know of a PPC app other than Pocket Streets that can use these maps? They are .mps files (not to be confused with the Mathematical Programming System file format). Ideally, I'd hope they could be used with a free app, like MS Live Search, as cached maps instead of needing the internet. That would be particularly useful when I drive through cell signal dead zones and it can no longer download maps.