I just recently started trying out NewsBlur to replace Google Reader, and I love how configurable and fast it is! Really a joy to use.
However, one little design niggle that I have with the web app is that the header containing the folder name, sorting logic, and “mark all as unread” button is not anchored so I have to scroll up through all of the story titles in order to mark the remaining ones unread.
I would love it if you implemented a minor design change that anchored that header. I am using the list on the left side of the story view in Safari, if that makes any difference.