There is a loot of buzz on the internet about web services and Ajax, SAJAX toolkit provides a simple interface to XMLhttprequest method which forms a part of the refresh less webpages, web applications and Rich internet applications that we see now a days.A PHP programmer can easily access his PHP scripts and functions via JavaScript thus making page or application dynamic and more interactive, the simplest example for this can be found here.
the most famous and popular example of this kind of technology can be found at google suggest and google maps