Bestajaxscripts.com is a large collection of AJAX scripts and free resources such as tutorials, videos of ajax script & generator.
They have many categories: DHTML, Web 2.0, chat scripts, rating scripts, polls scripts, flash scripts, upload scripts, etc.

Asynchronous JavaScript and XML or AJAX is a web development technique used for creating interactive web applications. The intent is to make web pages feel more responsive by exchanging small amounts of data with the server behind the scenes, so that the entire web page does not have to be reloaded each […]