Submitting  PDF files to different PDF document sharing websites is also another element of SEO and online promotion. In terms of SEO, you can create Do-Follow links that point to your site. Not only that, it also provides a way for you to market your products or services. If your document is interesting, most people would download the PDF to their devices, and if they really like it, they will share the document with their friends or family members.
Therefore, it is very helpful to create useful documents and then submit them to some high PR PDF submission sites. One thing you should bear in mind  is that you should ask yourself the following question when submitting the document to PDF sites: Why should people read your file, in other words, what benefits will they get, and you should never only talk about products or services. Anyhow, following are top 20 high PR PDF submission sites that you might want to submit your document to:

Websites	PR
fliiby.com	4
docs.thinkfree.com	4
www.edocr.com	4
pdfcast.org/	5
www.powershow.com	5
uploading.com	5
www.rapidshare.comhome	5
www.2shared.com	5
www.authorstream.com	6
www.smashwords.com	6
www.4shared.com	6
www.wattpad.com	6
www.lulu.com	7
www.free-ebooks.net	7
www.docstoc.com	7
www.dropbox.com	8
www.slideshare.net	8
www.scribd.com	8
issuu.com	9

Hopefully, this list can come handy when submitting your document. If you have more sites to add to the list, please leave a comment and let me know. I will consider them and add them.