Scribd is the “YouTube for Documents”

Scribd, launched last March, can be described as a text version of YouTube. It is a social network that lets you tag, share, and comment on uploaded documents (.doc, .pdf, .txt, .ppt, .xls, .ps, .lit). Documents can be displayed and embedded as html or in the Flash paper format. They can be downloaded as .pdf’s, .docs, .txt, and even .mp3 files. The mp3 version is created by Scribd’s text-to-speech package.

SlideShare, launched in October 2006, is a similar service, but for uploading (powerpoint or open office) presentations only.

You can also use these sites for example to pdf your document if you don't have pdf-software on your computer available and download the pdf-file to your computer and remove it from the Scribd site again.
Or find an interesting document on Scribd or SlideShare and use the html-code to embed the document in your course site. See an example of an embedded flash document in my test site (password only).