So it turns out the Dropbox removed the Public folder for new users a few months back. This actually threw me and a lot of my students - for several months I have been continuing to tell my students to use their public dropbox folders, and it has only just come to light that they didn't have one unless they created it explicitly. All good now, but it's a great example of poor visibility. Not dropbox's fault as such. Just something that's a problem with lots of online interactions - you can't see what the other person is looking at and you tend to assume that they see what you see. If you've got a Public folder you assume others have. You can say, well the students should tell you, but students are often overwhelmed and tend to assume, erroneously, that the instructor knows what they are talking about ... :-)
The Dropbox Public folder can still be created by any user who wants one and they are really really useful for quick testing of webpages, sharing images and so forth. So useful in fact I wish I could adjust the Ctrl-Shift-4 screen capture on OSX so that any screen capture would be immediately moved to my public dropbox folder and then the public url for it be added to my clipboard, so that I could go Ctrl-Shift-4 and then Ctrl-V into an IM like Skype text chat to immediately share what I am seeing with whoever I happen to be chatting to at the time.
What's interesting to me is how long it's taken to work out that this was a problem. The cut and paste screen shots feature that I mention above has been implemented in Linux by one of my past students, although it worked specifically with his own server and not with Dropbox. It's a potentially great solution to the problem of poor visibility when working with others online. Screen share via Skype or Google Groups is a great way to debug these issues, but it takes time to setup and the tendency is not to go there unless an obviously serious problem comes up.
I've noticed myself starting to prefer Skype text chat recently over email recently. Some people have laughed about that, "yeah right, because starting up an email client is so hard", however I think there is something important there. It's like being in the same room with someone and just being able to turn around and talk to them, versus needing to pick up the phone to call them. To send an email I have to go to my email client (I use Thunderbird and a few Cmd-Shift clicks on OSX will take me there), get a new message window open, start typing the person's email address, and then a subject line and then get my cursor in the main window. It's not huge, and perhaps it would be simpler in some webmail set ups, but it's all little cruft actions that get in between my thought and getting it across to someone.
For IM chat (in my case, usually Skype text chat) I just Cmd-Shift to that window and start typing. I may need to click on a different chat room, but it's pretty damn fast. Of course the dynamics of both email and IM change if you are actually responding to someone, but I really do find myself feeling like their is a lower barrier to the IM chat, and by arranging the groups of people in the different Skype chat rooms appropriately there's much better visibility than email, although that depends on how people are using Skype.
Some might argue that the lower barrier is a bad thing, causing myself, colleagues and students to spend all their time blathering in Skype text chat. Also, as Dave Patterson mentions in CS169.1X, there is the danger of communication addiction, where you are constantly seeking little dopamine squirts and find yourself checking for messages all the time.
However, this issue of Dropbox dropping the public folder only finally became clear to me as a result of chatting with a student in Skype text chat. Maybe it would ultimately have come out in an email or a forum post, and maybe it distracted me from doing something else important, but having at least a partial window into what students are going through as they try to complete assignments seems like it might be the most crucial thing for an online instructor. Or perhaps I'm just deluding myself in order to get another dopamine fix :-)