Is Scribd widely used in academia? Scribd is surely a huge website, but I was wondering if there are some data on its usage in the academic world as a means for sharing lecture notes or research notes.
I use it a little, and one of my colleagues uses it a little, but I don't get the impression that it's widely used. The application I used it for was the following. I have written textbooks for use in some of my courses. They're available for free online. About 70 other people are using them. At a certain point, I decided I wanted to do a fairly major revision, which would completely break compatibility with the earlier versions of the book. (There's a different order of topics, for example.) I didn't want the old versions cluttering up my web site and creating confusion, but I also didn't want to force my users to switch immediately to the new version (or at all, if they liked the old version better). So I just put the old ones on scribd.

One of my colleague uses scribd for his course notes, for a somewhat different reason. He simply doesn't want the hassle of maintaining his own web site, paying for webhosting, etc.

For both me and my colleague, one of the considerations was that our school's computing resources are flaky, inadequate, and Windows-centric. People might also prefer not to use a school server for something like a textbook that they want to make clear is not the intellectual property of their employer.

One of the problems with using scribd for these purposes is that scribd has been searching for a business model that will allow them to make a profit, and therefore they keep changing their rules and the way they present themselves publicly. For example, I've heard complaints from people that (at least at one point in time) scribd seemed to be trying to force them to pay money or contribute materials in order to access files.

It is probably not realistic to think of scribd as a permanent place to store documents (cf. arxiv.org or archive.org, where there is some expectation of permanence).

Another educational purpose for which I use scribd is illegal according to the laws of some countries. There are a lot of classic papers in my field that are very important and useful educationally, but are still under copyright in many countries. Some of the old ones are not even available from the publisher in digital form if you're willing to pay; they haven't been digitized, and the only way to access them is by going to the basement at a big university where they keep very old journals. Sometimes when I go to the trouble of obtaining one of these papers, I scan it and post it on scribd.