Google Maps has a wide array of APIs that let you embed the robust functionality and everyday usefulness of Google Maps into your own website and applications, and overlay your own data on top of them:
Maps JavaScript API

Embed a Google Map in your webpage using JavaScript. Manipulate the map and add content through many services.
Version 3 – Version 2
Maps API for Flash

Use this ActionScript API to embed a Google Map in your Flash-based web page or app. Manipulate the Map in three dimensions and add content through many services.
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Google Earth API

Embed a true 3D digital globe into your web page. Take your visitors anywhere on the Earth (even below the ocean) without leaving your web page.
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Static Maps API

Embed a fast and simple Google Maps image in your web page or mobile site without requiring JavaScript or any dynamic page loading.
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Web Services

Use URL requests to access geocoding, directions, elevation, and places information from client applications, and manipulate the results in JSON or XML.
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Maps Data API

View, store and update map data through Google Data API feeds, using a model of features (placemarks, lines & shapes) and collections of features.
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