Thanks for the feedback thus far. I will try to darken the background a bit. I am also planning on trying to make the header image a bit less tall.
With regard to the Google ad, when you say that it obstructed your view... Which page? Front page, or on the single entry page (or both)? And did it actually cover the text? It's supposed to be inserted between the first and second entry on the front page, and there's supposed to be a pair between paragraphs 1 and 2 on the single entry page for those entries that were long enough to be broken with the <more> tag.
I am using a Mac with FireFox, Safari, and IE and have not seen any instances in which the ads overlay the text. They shouldn't and, if they do, I need to fix something.
Thanks again for the feedback -- keep it coming!