Whenever I have spare time, I like to go to Bruegel site and check their section on publications in macroeconomics. Here I usually find small publications of 20 something pages. The size is just about right. It's not as difficult as some papers, but it has as much content as one. For me it strikes the exact balance between a small article in the newspaper and a scientific paper.
I was wondering which think-tanks, or which other sources for this type of publications, do you use? And why?