Fancy Hover Box/Image Effect

Hoverbox Image Gallery is a super light-weight (8kb) roll-over photo gallery that uses CSS. It pop outs an image without affecting the page’s layout.

Source: http://sonspring.com/journal/hoverbox-image-gallery
View Demo: http://host.sonspring.com/hoverbox/

Fancy Thumbnail Hover Effect w/ jQuery is a nice tutorial that teaches you how to add a nice hover effect to an image. A bigger image pops out above the thumbnail.

Source: http://www.sohtanaka.com/web-design/fancy-thumbnail-hover-effect-w-jquery/
Demo: http://www.sohtanaka.com/web-design/examples/image-zoom/