Here is an attempt to port Google Maps to the PSP with a simple interface. This program is not using the Google Maps API, it is retrieving the images directly.

Controls:

Digital pad: move the map.
Analog pad: move smoothly the map.
R button: zoom in.
L button: zoom out.
A/B/X/Y: change view.
Start: menu.
Source code: PSP-Maps

Changes:

added a cache on the memory stick
allows offline browsing of maps in the cache
added a configuration file
added options to disable disk cache and transition effects
added an error image when view is not available
better zoom level (thanks to elefas for the tip)

http://royale.zerezo.com/psp/