CSS3 is becoming a reality, providing rounded corners, drop shadows, real fonts, gradients, animations and more. The support is good in Safari, Chrome, Opera and Firefox browsers, and most of these effects will just degrade harmlessly in Internet Explorer.
At DrupalCon 2010, Jen Simmons gave a great presentation on CSS3 and shared lots of useful tools. This screencast gives a quick tour of many of these tools and resources.