Recently got asked to redo the EBS: European Business Solutions site as it was a bit outdated code wise and we thought it could be a bit friendlier to search engines.
The original code was done in an old HTML editor and so contains a lot of font, span, div tags and all the other html that just bloats up a page and can now be replaced by my wonderful friend CSS.
In order to make it as search engine friendly as possible i wanted to shift as much of the code into a single CSS file used accross the site. This means that the ratio of relevant text to code tags on a page is quite high which can help increase your search engine rankings.
Its definately worth doing on older sites. For starters, it can save loads of bandwidth!
I'm a web developer based in the East Midlands, UK and if I keep up the current rate, I might have developed 3 million sites by the time I retire