I am extremely proud of the navigatory tabs on the ICSA web site. They may not seem extraordinary at first, but if you hover over any link in the navigation bar, you will notice that the dividing lines on both sides of the link disappear. The dividing lines are background images set on the links, so there can only be one per tab, positioned to the right so they sit where the link ends, and yet the blue covers it's own and it's neighbour's without the link jumping.
The solution is pure CSS, taking advantage of relative positioning. I used the same technique, although in a slightly different way, utilising images, for the Reed Insurance web site.
It may not seem like much, but I feel it adds a much more professional and elegant touch. If I had left a single, detached white line hanging off the side of the bright blue highlighted area, it would look out of place and it would make the site as a whole feel half-finished. I have been told I'm overly meticulous, but I think it's little details like this that make or break a web site.