PUBLIC MARKS with tags ajax & library

Offline.js is a library to automatically alert your users when they've lost internet connectivity, like Gmail. It captures AJAX requests which were made while the connection was down, and remakes them when it's back up, so your app reacts perfectly. It has a number of beautiful themes and requires no configuration.

Really Simple History is a lightweight JavaScript library for the management of bookmarking and browser history in Ajax/DHTML applications. RSH serializes application data in an internal JavaScript cache so that bookmarks and the back button can be used to return your application to an earlier state. Originally developed by Brad Neuberg in 2005, RSH has won a large user base for its simplicity, ease of use and lack of dependency on any specific Ajax framework. It's written in plain old JavaScript and can be included on any site according to the terms of its BSD license. In September 2007, Brian Dillard of Pathfinder Development came on board as maintainer and ongoing code steward for the project. A new version, with support for additional modern browsers (IE7, Safari, Opera), was released as RSH 0.6 on December 3, 2007.

Google offers permanent hosting for major Ajax libraries

Comparison of various scripts that display images and other objects in somehow cool CSS popups