Speaking of Google apps, gMaps (free) and gMaps Pro ($1.99) are fairly popular unofficial Google Maps applications that have been around for awhile. Version 1.10 just hit the Marketplace and as with each version, it keeps getting better and better--so good in fact, we're ready to give it a big thumbs up.
The latest version gets some theme support (uses your accent color), zoom buttons, geo-location info for any object and a few other tidying up features.
We like it for the alternate view to Bing maps, the traffic info (including "follow me" for tracking) and the layers for viewing (street, hybrid, physical, water-overlay, satellite). The ability to "screen shot" the map to send to others is pretty smart and if you're in the city like us, the public transport layer is quite handy for finding that subway.