An excellent article on how to make some really dynamic websites that work well on everything from a widescreen monitor to a smartphone held vertically with just CSS and HTML. Read through the whole thing and look at the demos while resizing your browser - wow.
"Fluid grids, flexible images, and media queries are the three technical ingredients for responsive web design, but it also requires a different way of thinking. Rather than quarantining our content into disparate, device-specific experiences, we can use media queries to progressively enhance our work within different viewing contexts. That’s not to say there isn’t a business case for separate sites geared toward specific devices; for example, if the user goals for your mobile site are more limited in scope than its desktop equivalent, then serving different content to each might be the best approach."