Group small images (e.g. the website’s interface images) in one larger image called a sprite sheet
This process significantly reduces the number of HTTP requests. There are several free online services for generating sprite sheets (Project Fondue’s CSS Sprite Generator, CSSsprites.com and SpriteMe.org).
Here are the addresses of a few sprite generators:
http://csssprites.com
http://cssspritegenerator.net
http://spritegen.website-performance.org
http://spriteme.org
http://csssprites.org
http://css-sprit.es
http://wearekiss.com/spritepad
http://draeton.github.com/stitches