This is best for instant uploading pdf, support large format and a lot of people read books from this website. And easy to use.
http://www.scribd.comExternal ↗
In google docs you cam make a large format documents and share it, and also to create documents with images https://www.google.com/docs/about/External ↗
But on this website's you need to cut pdf in two or three parts.
http://issuu.com/homeExternal ↗
http://www.slideshare.netExternal ↗
http://www.docdroid.netExternal ↗
Take pdf and other from here and do not share books or copy books from non Temple of Zeus authors, that is illegal. But you are free to copy and share pdf from Library of Thoth, just do not change it.
Also you maybe can have use from this website http://www.guerrillamail.coExternal ↗m