PreZentit - Prezentit is an online presentation solution based on JavaScript that comes with new online collaboration tools.
DocDroid - DocDroid is a service for sharing document and slides.
authorSTREAM - authorSTREAM enables presenters to upload & share PowerPoint, Keynote & PDF presentations online; embed in blogs, convert to video and share on social networks.
SlideShare - Discover, Share, and Present presentations and infographics with the world’s largest professional content sharing community.
Present.me - Present.me - the video presentation platform. Share all your presentation content in one place. Slides, slides and audio, slides and video or just video. No software to install, all you need is your slides, a webcam and YOU!
Scribd - Unlimited books, audiobooks & comics. Unparalleled discovery. Any device. $8.99/month