Creating fancy buttons just got more easy with CSS3. You can apply gradients, shadows and corners to elements without using images. Using CSS3 for your buttons make it easy to apply changes like font-size or padding. The techniques used here can be applied to any element such as button, input, a, span, div and so on. read more about css3 button tutorial

Since web 2.0 is the usage of gradients almost a must. Small background images were created for navigation menus, different sections or entire layouts. And when wanting to apply light changes like the height you needed to reconstruct the image(s). With CSS3 you can create gradient backgrounds and apply changes without much effort and it saves HTTP requests for images. Unfortunate do the layout engine not agree yet on the implementation of gradients. read more about css3 gradients