If you work with responsive designs, you’ll perhaps be interested to learn that amongst the current working draft of the CSS3 Fonts module is reference to ‘viewport relative’ fonts: http://www.w3.org/TR/css3-values/#viewport-relative-lengths. The ‘vw’ unit (for viewport width), ‘vh’ unit (for viewport height) and ‘vm’ unit (for viewport minimum – equal to the smaller of either vm or vh) could be crucial time savers in the years to come and save the slight tedium of px to em or rem conversions. Sadly, there is no browser support for vw, vh or vm font units at present. It’s therefore a matter of watching the browser nightly builds for any implementations we can test it on. At present, I’m informed that only IE9 offers support for the new units. Certainly Firefox 7, Safari 5.1 and Chrome 15 don’t.