The MAPS.ME Android SDK by MAPS.ME allows developers to integrate offline maps into their Android applications written in Java. MAPS.ME's maps cover all cities in all countries. These maps are highly detailed and zoom in and out smoothly.
This fall the New York City Mayor's Office of Film, Theatre and Broadcasting will celebrate its 40th anniversary with the publication of a book, Scenes From The City, and a series cultural events across the city. But in addition they have created an excellent web mashup: Scenes from the City Interactive Map.