By way of Scott on twitter, I discovered the Google Ajax APIs today (thanks to Douglas Purdy for the original tweet). The playground area allows you to see all of the APIs in action. Taking a step back, you can view all of the APIs that google provides by visiting this URL: http://code.google.com/more/.

All you need to get started, is to sign up for a free API key, which you can do here. Then just add a script src tag to your page referencing your API key (http://www.google.com/jsapi?key=ABCDEFG) and you are good to go. I would recommend reading at least the Getting Started guide under documentation. In addition to the stuff you would expect, like search and maps, they also have language translation and visualization (charts and graphs) to name a few. They also provide up to date versions of common APIs like JQuery, relieving you of the burden of managing these resources on your own.

While I would certainly use the Google APIs for accessing Google content, I am a little concerned over some of the other offerings. I would prefer to control when I update my JQuery library for example (how do I know if there are any breaking changes)?