Originally Posted by Andrew R

I'll pick the rest out later but this if the first one I came across.

Note the empty span tags in the navigation: http://www.matthewrochow.com/projects/driven/

Also on that same page, search for these:
<a href="#" class="button"></a>
<li id="m5"></li>
<div class="abox-bt"></div>

You use some of those multiple times.

etc... do you want me to continue onto your other work?

Also, as for unnecessary ones, you could've easily gotten rid of many of your wrapping/content divs. You don't need a header container, you only need one to wrap around the entire content (the top image could be the background of the navigation, the bottom image could be on the footer, main background on that one div), and you don't need so many inner ones.