What’s a useful API service to do?

What’s a useful API service to do?

A GUI is a graphical user interface for humans. An API is an application programming interface for machines. Ideally, a machine API ought to be able to access all of the human GUI functions of your site or service.

For API ideas, see my answer to:

• What are the current sub problems that I could address in summarization, or what would you like a summarizer to do for you?