Google AJAX APIs
From Seo Wiki - Search Engine Optimization and Programming Languages
Google Maps API
Add a Google Maps to a web page.
Google AJAX Search API
Integrate Google search into a web site
Google AJAX Feed API
Google Visualization API
Create visualizations and reporting applications that access structured data in a common format.
AJAX Libraries API
Access popular AJAX libraries directly from Google's servers.
Google Earth API
Add Google Earth to a web page.