Google codes

The greatest thing about Google and which sets it apart from its main competitor Microsoft is that while MS is known for its priced softwares, Goolge always provides free stuff to its users.

I think you should go to http://code.google.com/ , It has a huge set of Open source codes and APIs(A set of routines that an application uses to request and carry out lower-level services performed by a computer's operating system. Also, a set of calling conventions in programming that define how a service is invoked through the application.)

I think you should check out atleast the APIs that are with reference to Adwords and Blogger. These are two things that we might be using so very often.