Heh, reading that link, one of the basic things I've used closures for lately is filtering a list in different ways. I had one utility function that goes into a loop parsing email files from a directory (and if successful, finally returning the attachments from the one you want according to some parameters) and skipping files that it's already seen before. Then I found that in some particular case I needed to call the function multiple times and have it remember what it had seen from the previous call. So I turned the filtering function into a parameter, allowing you to maintain the hash of 'seen' email files outside of the loop in the main function (but keeping the original behaviour by default, which is what I want most of the time). Pretty basic example...but there it is.