An impressive collection. I clicked through a significant number of links and can definitely see the utility of these sites in (and out of) the classroom for informal learning. Drawback: Found the interface to be so overloaded with advertisements that it can be difficult to ascertain whether the site is a legitimate collection of learning sites or not. I would say this is the only weakness of the site.
All sites appeared to be currently working/updated. I didn't find any broken links.