Many researchers have used academic social platforms such as ResearchGate and Academia.edu. However, many publishers have begun cracking down on such for-profit ventures, issuing takedown notices for academic works posted there.
In response, a number of noncommercial research sharing platforms have sprung up, that operate on a not-for-profit basis and with broader support for principles of openness. Though researchers must still be careful to abide by the policies of their publishers when sharing work on these sites, they are good alternatives to the commercial sites that many publishers strictly forbid and useful tools for increasing the discoverability of your research.
(No matter what site you use, consider linking to your works in Chapman University Digital Commons instead of uploading directly. Because the policies for all works in Chapman University Digital Commons are carefully vetted before upload, you can be assured that you will be directing users to a secure, stable version of the work. This will also help you consolidate all your download statistics in one place, rather than having to manage them from several sites.)