Web APIs
An application programming interface (API) is a source code interface that a computer system or program library provides to support requests for services to be made of it by a computer program. An API differs from an application binary interface in that it is specified in terms of a programming language that can be compiled when an application is built, rather than an explicit low level description of how data is laid out in memory (WKP).
Google Map APIs (WKP).
Yahoo! Maps APIs [http://developer.yahoo.com/maps/index.html]
Java APIs
Java API for XML Web Services
The Java API for XML Web Services (JAX-WS) is a Java programming language API for creating web services. It is part of the Java EE platform from Sun Microsystems. Like the other Java EE APIs, JAX-WS uses annotations, introduced in Java SE 5, to simplify the development and deployment of web service clients and endpoints.
The Reference Implementation of JAX-WS is developed as an open source project and is part of project GlassFish, an open source Java EE application server. It is called JAX-WS RI (For Reference Implementation) and is said to be production quality implementation (contrary to the former Reference Implementation being a proof of concept). This Reference Implementation is now part of the Metro distribution[1].
JAX-WS also is one of the foundations of WSIT. WKP
Books
Professional Web APIs with PHP: eBay, Google, Paypal, Amazon, FedEx plus Web Feeds by Paul Reinheimer (Wrox, 2006) ISBN-10: 0764589547
Professional Development with Web APIs : Google, eBay, Amazon.com, MapPoint, FedEx, by Denise M. Gosnell. Wrox (April 15, 2005). ISBN-10: Amazon-com%2Fdp%2F0764584456%3Fie%3DUTF8%26qid%3D1186331292%26sr%3D1-2&tag=humpathcom07-20&linkCode=ur2&camp=1789&creative=9325">0764584456
Mining Google Web Services: Building Applications with the Google API, by John Paul Mueller (Author). Sybex; 1 edition (April 23, 2004) ISBN-10: 0782143334