HTML5

Main link: www.whatwg.org

Examples: www.whatwg.org/demos
Specifications (drafts): www.whatwg.org/specs

With reference to AJAX: www.ajaxplanet.ru/novyie-formyi-html5
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Alternative specification: simon.html5.org/html5-elements

In wikipedia a bit: en.wikipedia.org/wiki/HTML#HTML_5.0