AxsJAX

AxsJAX (Access-Enabling AJAX) is an open source JavaScript library for enhancing the accessibility of Web 2.0 applications.
One of the key abstractions that AxsJAX provides to web developers is the ability to cause assistive technology (AT) to speak. Although AT do not provide such an interface to web developers, they do respond in predictable ways to events. By using WAI-ARIA, AxsJAX is able to manipulate the DOM such that an ARIA-aware browser + AT combination will generate and receive the necessary events which cause the AT to speak what the web developer wishes to be spoken.
Another abstraction is a content navigation rules system built around the idea of multiple trails through a page. Users can select which trail they wish to be on and then navigate through just the items in that trail. For example, on a news site, the trails may be the different sections (Politics, Entertainment, Tech, Health, etc.) and the items in each trail would the stories in their respective sections.
AxsJAX scripts can be included by the web application developer (as in the case of Google Reader), automatically applied on behalf of the user by their AT (e.g., Fire Vox), or manually inserted by the end users themselves via a bookmarklet or Greasemonkey script.
Applications of AxsJAX include using it to create a talking translator 
and mashing up the xkcd web comic with its transcripts.