CSS Rounded Corners Roundup includes a table of most known techniques
Centering a DIV shows a couple of techniques to center a div tag.
Listamatic provides a collection of techniques to render lists in different ways (images, tabs, etc.)
CSS Tabs shows how to render a list as tabs
CSS submit buttons shows how to decorate buttons with CSS and make them nicer.
Styling submit buttons with images shows how to style a button with a single image.