DocSlide - DocSlide is an online document and knowledge sharing platform.
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.
VCASMO - VCASMO is a multimedia presentation solution for photo and video slide shows, business presentations, training, academic teaching, sales pitches, and seminars.
Scribd - Unlimited books, audiobooks & comics. Unparalleled discovery. Any device. $8.99/month
projeqt - With Projeqt, your presentations never remain static. Pull in live tweets or blog feeds, insert an interactive map, add audio notes or stream videos. Let your presentations be as dynamic as you are.