Idea for the "link to out-of-browser"-problem: couldn't scribd offer a kind of hotlink to display PDF-documents from the web in their viewer? That is, instead of linking to http://wherever.com/mystupid.pdf, one could link to scribd.com/show?url=http://wherever.com/mystupid.pdf
Would something like that be legal, or would it make scribd suable for stealing content?