Framework
http://www-949.ibm.com/software/rational/cafe/community/egl/ce - EGL Community Edition Hub (IBM Ajax Framework)
JavaScript / AJAX
http://www.phatfusion.net/imagemenu/ - horizontal menu, reveals more of the image as you rollover it
http://www.ajaxplorer.info/
http://www.dojotoolkit.org/
Applications
http://www.pixlr.com/editor/ - Web image editor