If you look at the source code of the majority of the websites, you can see that their layout (navigation bars, titles and so on) is obtained putting contents in <table> tags. This is a very bad way of writing, because in consists in using tags in different ways from the way they have been created for. Neil Crosby, webmaster of www.workingwith.me.uk, has thus started a campaign for using the tables for tabula data, leaving the layout stuff to the CSS sylesheets.
I joined the campaign, as you can see in the "Validated!" section of the right menu. In the Italian version of this page, I put a complete translation of the page in which Neil esplains the advantages of avoiding the tables in defining the layout.