My favorites Jquery ajax librarys / plug-ins

PrettyGallery

http://www.no-margin-for-errors.com/projects/prettygallery/

PrettyPhoto

http://www.no-margin-for-errors.com/projects/prettyphoto-jquery-lightbox-clone/

Carousel

http://sorgalla.com/projects/jcarousel/#Examples

NyroModal

http://nyromodal.nyrodev.com/

MegaMenus

http://www.sohtanaka.com/web-design/mega-drop-downs-w-css-jquery/

Coinslider

http://workshop.rs/projects/coin-slider/

Nivoslider

http://nivo.dev7studios.com/

Flowplayer

http://flowplayer.org/

Jquery Tools

http://flowplayer.org/tools/index.html