One thing that has always been a struggle is how to perfectly center an object (for example, a DIV) both horizontally and vertically on a page.
The other night I was searching for a better way to do this via CSS instead of using nested tables. I came across Dead Centre, a website that demonstrates exactly how to accomplish this. You can see some of the detail on the webpage itself, but also take a look at the source for more details on how this was executed.
This provided a truly dynamic design that was 100% CSS-based and works across all browsers.