One of the sites we found is ReadWorks.org. There are tons of lessons organized by concepts of comprehension such as author's purpose, main idea, or theme. I haven't looked at all of the lessons, but I found many with great ideas and quality printables. The only downside is that many are built around particular books that you'd have to purchase or collect from the library. However, I already owned several of the titles because the lessons use popular literature.
I'm hoping to see the site grow to provide more than one unit for each topic. Even if it doesn't, it's still another resource to add to your grab-bag. Click on over to check it out.