Your reviews were a breath of fresh air among the numerous stink clouds I've sifted through by people who have made but 4 posts over the years. I'd like to take the time to do the same for you.
My first thought was "
oh boy, a leaderboard made to look like a header". I'd be interested to hear later on how that slot does, I'm thinking a lot of people would assume it's just an odd site header and ignore it past that. Then again, if you don't have a high bounce rate maybe people will click it trying to get to the home page. I guess I've got mixed feelings about that spot, I definately want to know how it does with clickthroughs.
I really like that light green you're using for the background. I don't know about that 1px black(?) border around the content wrapper though, it seems a little fuzzy to me. I think a 2-4px border might look better.
I'm thinking your Adsense skyscraper in the sidebar is off on the background color. It's currently FFFFFF but the containers background is EEEEEE.
I noticed you have a handfull of categories with only one entry. I always groan when I see that. It's a good idea to have
at least two items in a category.
One thing I've thought about doing is never creating a category to place a post in, but rather only adding posts to existing categories, then going through posts every few months looking for common subjects that could use their own category. Then creating those categories and adding all of the posts to them at once.
You should take another look at the results of that "Valid XHTML" link.

Strong with this one, the sudo is.