Hi, A banner at the to of the page would be better than a link unit in my opinion (do the same than here on the forums) As for the skyscraper ad unit on the left, I think it's not in the "flow" of what the visitor look. As you can place 3 ad units and I only see one, I'd add a 468*60 banner at the end of the two first posts of each page. They will be in the flow of what the user see: the user will see the post, and then he will naturally see the ad. You can also put an AdSense for Search box, it's free and it should bring you a few additional clicks every once in a while.
You have a ad unit on top-right side. I suggest you put a 336*280 or 250*250 ad unit on the top of the post. Also, use more than just one ad unit. You can put 3 ad units + 3 link units + 3 referrals + 2 search boxes.