The extra space below the menu bar seems to be caused by a <br /> break tag on line 250 of the HTML.
The surrounding code looks like this:
<!-- / nav buttons bar -->
<!-- get rid of blank line -->
<font color='red'><br /></font>
<!-- NAVBAR POPUP MENUS -->
<!-- community link menu -->
Of course, that may not be the space that you are talking about. So, another possibility might be the height of the <table> in which the ads are placed. It has a height of 120px and the ads seem to be around 90px high, so it is effectively giving you a 15px space above and below the ads.
Hope this helps you find the culprit.