I live in Germany and read David Allens book several years ago. At the beginning I was wondering what kind of folders he was talking about. Then I figured, that german "Leitz" folders are something completely different than the folders David Allen ment. 

This is a typical german folder (you need a hole puncher and it collects hundreds of pages): 


But these are the kind of folders Mr. Allen was talking about (slim, keeps only few pages): 


It required some search, but luckily these folders are available in germany, too. I buy mine at classei.de, but mappei.de also offers them. Moreover I bought an open rack, filled with 6 boxes where I have instant access to the folders. I don't need to open a drawer or anything else. That system works very well for me - and even my wife ;-)

What folders do you use?