Get placeholder images according to your need when designing a new web app

I could find not one but three of them. Besides choosing sizes, we can also choose type of images we want from categories provided, all for free.

Lorem Pixel
Fakeimg
Placeimg

Sencha gives you a free way to resize your big images on smaller screens.

Link here.

Load high resolution image for retina display screens

Link here.

Tutorial to create an animation on canvas using image sprites.

Link here.

A flyout image slider using jquery, css3

Link here.

Cool image visualisation jquery plugin

Link here.

Different image transformations in one plugin

Link here.

Jquery to know if user's browser can display high-res images and/or has the bandwidth that fast to show those images.

Link here.

Various solutions for rendering good images on different dpi screens.

Link here.

Load images when they come in user's viewport

Link here.
This jquery plugin only loads the images when they come in the user's viewport.

Slideshow using impress.js

Link here

Nice slideshow viewer using impress.js (click this first if u don't know the impress.js awesomeness) !
Works in chrome and firefox.
Has a fix for IE 9. 

Slider using css

Link here.

Responsive css slider without using javascript.
doesn't work in IE 8 though.