Image sprite is a collection of images put into a single image depends on particular position of a image.
Basically CSS sprites are used for faster loading of your site.
Read our previous article about CSS Image Sprites.
There are few online CSS Sprite generator tool which is very handy to create sprites quickly.
1) CSS Sprite Generator
CSS sprites are a easy way for reducing the number of HTTP requests which is made for image resources referenced by our site and those images are combined into only one larger image i.e. at defined X and Y coorindates.
2) Drupal Data URI Sprites Generator
Here the module parses aggregated CSS files for images and removes images from it, generating additional CSS file which contains images in Data URI format.
3) Drupal CSS Sprite Generator
Feel free to provide the feature requests on which you would like to view for the future of this module.
4) CSS Sprites Generator
Make image sprite using CSS sprites generator.
5) CSS Spritegen
CSS sprites allow you to upload multiple images and combine into a single file for reducing the number of HTTP requests and speeding up page loading.
6) SpriteMe
Install SpriteMe by dragging limk to your bookmark toolbar or right click to add it to your favorites.
This article is quite informative. I used some of these tools. Finding it unsatisfying is really optimizing the images to minimum possible. I wrote my own which I host at CSS Sprite Generator. Hope you try it out.