I've recently been using a number of online project management tools. One feature I really like about them is their ability to mix content/context with individual files and their ability to help you keep track of activity, thus making it visible.
For example, many of these tools allow you to upload a file as part of a comment or message. You get the file AND the message that provides the context for the file (or extra 'must know' information about the file). Even better, other people can then contribute by adding their own comments or replies. They can then upload additional versions of a file (or extra files) and this is logged on the page - right next to the files making this information clear and visible. Even better, you can choose to be notified when files are added or amended, making important changes visible even when your attention is elsewhere.
Another helpful feature is organising the world according to projects and mixing different tools. You can set milestones, have discussions, assign and receive tasks and many other things, all in the same web application.
I see no reason at all why these features should not be available in the standard file managers that come with Mac or Windows. How much more useful they would be if you could start to fill them with useful information (look at all the READ ME files people put in folders as a way to 'fudge' this discussion functionality).
As mentioned earlier, where things are visible and where context and intention is clear, the whole workflow immediately becomes more usable and pleasant.
