blank space under posts

It’s not unused ad space – it’s CSS. Change style.css (line 440) from:

.post {
background:#F9F9F9 none repeat 0 0;
margin:0 0 40px;
padding:5px 10px;
text-align:justify;
}

to

.post {
background:#F9F9F9 none repeat 0 0;
margin:0;
padding:5px 10px 0;
text-align:justify;
}

And change style.css (line 554) from:

h2 {style.css (l
margin:30px 0 0;
}

to

h2 {
margin:0;
}

Doh! Didn’t think to run a validation check.