Google provides a large selection of tools and APIs for web developers to use in their projects. These APIs allow access to functionality within Google's services such as Maps, Docs etc.
Here a few ways to view and browse the full list of products that are available.
The first method is the Google Code List page.
The other useful view is the Google Code Graphical Table. This displays all the tools and APIs in a colour coded grid.
For some reason Google don't seem to make this table easy to find.
These are two pages worth bookmarking if you use any Google services in your web projects.