AjaxDaddy and MiniAjax

All for free, this site has some excellent DHTML and AJAX code you can download. Under Drag and Drop it even has the basics of an AJAX homepage:

http://www.miniajax.com/

A large collection of nifty web 2.0 tools:

http://www.ajaxdaddy.com/

Prototype Window:

http://prototype-window.xilinus.com/samples.html

AJAX poller script:

http://www.dhtmlgoodies.com/index.html?whichScript=ajax-poller

A library of DHTML and Ajax scripts:

http://www.dhtmlgoodies.com/

Dynamic Content:

http://www.dhtmlgoodies.com/index.html?whichScript=ajax-dynamic-content