You can upload one or more documents without even signing up. Scribd supports Word, Excel, PowerPoint, PDF and other popular formats. It features an embedded viewer that lets you read documents online, so there’s no need to download anything. However, you can download documents in a variety of formats; print them; view them full-screen; and even hear them read aloud. If you do sign up, you can see various analytics about your documents, such as how many people read them and from what locations.
This could be very useful for educators, although I would imagine probably those in further/higher education. If you’ve used it successfully, let us know in the comments below!