SlideShare offers a free place to store and share presentations. As often as not these take the form of PowerPoint shows, but SlideShare also allows for sharing documents such as PFD files. Users set up free accounts to which others can subscribe; those uploading materials can decide whether to limit viewing only to their subscribers. Links to materials are generated so that users can share them. Like Google Docs, SlideShare would be useful for trainers wishing to distribute a PowerPoint show or PDF file via Facebook, Twitter, or another social networking site.