Imagefit is a simple, lightweight jQuery plugin to make images fit anywhere and anyway.
imagefill.js is jQuery plugin for making an image fill its container. It can be useful tool for responsive web design.
CollagePlus is jQuery plugin that arrange your images to fit exactly within a container. You can define the padding between images, give the images css borders and define a target row height.
imgLiquid is a jQuery plugin to resize images to fit in a container.