Comment Xastir (Score 2, Interesting) 190
I've replaced google earth with Xastir. Xastir is for ham radio station tracking but it featurs address lookup, multiple map layers, online maps, tigermaps, and gps support. When I was a cab driver I could use xastir to look up addresses offline because it's address mappings are stored locally. It doesn't look fancy, but it does look professional.
http://www.xastir.org/