CSS
"Cascading Style Sheets (CSS) is used to help readers of web pages to define colors, fonts, layout, and other aspects of document presentation. It is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation (written in CSS). This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, and reduce complexity and repetition in the structural content." -- wikipedia.org
This means that sites created using CSS are normally easier for search engines to read, making its appear higher in rankings, as well as being able to create layouts based on browser or reader type, which means your site should look good if your looking at it on a MAC, PC, Linux or even a mobile phone.
To the right you can see a selection of the sites made using CSS
