DocDroid - DocDroid is a service for sharing document and slides.
SlideShare - Discover, Share, and Present presentations and infographics with the world’s largest professional content sharing community.
iSpring Cloud - Share PowerPoint online on any device. Perfectly preserve all advanced PPT effects, interactivity and embedded rich media in your presentation. Use it free!
Scribd - Unlimited books, audiobooks & comics. Unparalleled discovery. Any device. $8.99/month
Docshare.tips - You can upload your documents.
Speaker Deck - Speaker Deck is the best way to share presentations online.