BttrLazyLoading is a Jquery plugin that allows your web application to only load images within the viewport. It also allows you to have different version of an image for 4 different screen sizes.

LaziestLoader is a responive-aware lazy loader, mostly for images...

Themeable progress bar library.
Allow to show image loading progress when using lazyload

What is bLazy? bLazy is a lightweight lazy loading image script (less than 1KB minified and gzipped). It lets you lazy load and multi-serve your images so you can save bandwidth and server requests. The user will have faster load times and save data loaded if he/she doesn't browse the whole page.

Lightway version of Lazy Load with support for serving
high-resolution images to devices with retina displays

Random & Responsive HTML 5, CSS3 Gallery with LazyLoad