I stumbled upon Scribd the other day. And I am really impressed. Such a simple way to store and share documents and yet so powerful. Scribd is a free online library where anybody can upload .pdf, .doc, .ppt, .xis, .txt etc. It also has an embeddable PDF player that let's you view documents right away in your web browser.
What I also like is the Digg-like rating system and the detailed traffic analytics for each document. Other very useful information like: recently uploaded documents, most viewed and similar documents makes this service leaves other document-sharing services I have seen way behind. You can also subscribe to other peoples documents via RSS which is very cool. If done right, Scribd could become the default destination for uploading and sharing everything from dissertations, papers, research reports, PR and marketing materials. The question is just how they will deal with all the garbage that people will start uploading..
If I would be Google, I would immediately incorporate the main ideas from Scribd into Google Documents.. it's really a no-brainer.