CSS Pseudo-classes
Pseudo-class are an interesting group of selectors in CSS that apply to elements when they're in a certain state or condition. The most prevalent use of pseudo classes is to style the various states of text links.

CSS Square buttons
These buttons use the sliding doors technique of CSS, plus two sliced background images with "on" and "off" states, to create flexible glossy looking CSS buttons. Each button can accommodate text of variable widths and supports a hover effect when the mouse rolls over it. The only limitation is the height of the button, which is fixed based on the background image's height.

CSS3 Gradient Menu Buttons
These fancy looking buttons brings together CSS3's border-radius, box-shadow, and linear gradients to create glossy looking menu buttons that use NO images.

Flipboard CSS buttons
Flipboard creates a series of CSS buttons that flip horizontally on themselves when the mouse rolls over them, creating an elegant, eye catching effect. It employs CSS3 transform and transitions to do the heavy work.

Spinning icons using CSS3 transform
An effect that seems to be popping up with increased frequency is the spinning image, or more precisely, icons. Move the mouse over an icon, and it spins (rotates) on its axis to draw attention to itself. This is realized using CSS3's transform: rotate(xdeg) property.