
UI components like galeries, accordian menus, charts, navigation all done with pure CSS. Good all around collection.
Though not essential as the title may imply there are some really nice tools. From jQuery to PHP and some Ajax tools range from forms, graphs, maps, color pickers, calenders and even more. Good list but not all "essential" just nice to have/know about.
good list of tutorials and best practices for using HTML 5 and CSS3.
There are exciting new features in the pipeline for Cascading Style Sheets that will allow for an explosion of creativity in Web design. These features include CSS styling rules that are being released with the upcoming CSS3 specification.