I'm not sure what you mean by "document sharing sites." There are places like StumbleUpon where you can share pages you found online with others. (Of course, you can do the same thing via Twitter, Facebook, Google+, etc. as well.)
Those may bring you some direct traffic. There are questions as to how much "quality" that traffic might have, since it tends to be people who were curious about the link as opposed to people who are seriously interested in what you or your company might have to offer.
As to SEO, usually the links from these sites are nofollowed in order to discourage so-called "SEOs" from spamming the sites with tons of their (or their clients') pages in an attempt to boost rankings. So they don't help much, if at all, with rankings.
As I've mentioned in other posts here, those are cheap & easy links -- that is, links that you can create yourself, for free. Google doesn't value those sorts of links as highly these days, with good reason.
Then there are article repositories, where people would "share" articles they'd written with the idea that others would pick them up and publish them on their own sites, with a link back to the original author's site. However, now that Google has started cracking down on duplicate content, this sort of article syndication/sharing isn't as attractive as it used to be.
Finally, there are document sharing sites like Google Docs where you and others in a workgroup can share files and collaborate on group documents. Those are usually private and would have absolutely no effect on SEO.
So the short answer is, "no, document sharing sites aren't going to help you much with SEO," no matter which type of document sharing site you're talking about.