Well, I have to say that what they are compiling is of very narrow utility - in my view any way. I have never selected class readings based on what is most popular, although it is intetesting to see what others use.  When I go do my own "syllabi crawling" on the web when designing or redesigning a course, I look for much more, specifically how the course is taught, what goes on in the classroom,  kinds of work/projects assigned, grading criteria, what level the course is taught at, etc.  I would much rather see a selection of actual syllabi, I learn much more from that than what these folks are doing -  at least so far anyway.