SlideShare – A Place to Share & Discover Slideshows. ‘SlideShare is a free service for sharing presentations and slideshows. You can upload your PowerPoint, OpenOffice, Keynote or PDF presentations, tag them, embed them into your blog or website, browse others’ presentations, and comment on individual slides.
What’s more, the transcripts of your presentation will be indexed by internet search engines and show up in search results. It’s a great way to share your ideas with others or to learn from other people. And it’s free.’