I've been away from the web2.o scene developments for a long time now as well as some of the amazing on-line tools that turn up almost on a daily basis.
One such website I recently discovered is called ISSUU, best described as a Youtube for publications. What I like about it is the eye friendly browsing of the documents. I embedded a document below. The document I used as an example is called: "What Muslims did". Click on the view in full screen button so you can see the document at its best. I have to say there isn't many Arabic documents in the website. Addendum: Discovered a similar website to ISSUU called YUDO.