1. Google Docs Presentation
   Google Docs is a freeware web-based office suite provided by Google within its Google Drive service. You can make and edit documents online while collaborating in real-time with other users.
2. Apple Keynote
   Keynote allows you to create captivating presentations using powerful tools and impressive effects. Keynote offers 44 beautifully designed basic themes. Create presentations in Keynote on your Mac and access them from your iPad, iPhone, and iPod touch. Changes you make to a presentation on one device automatically happen on all of your devices. This way, you will have the latest version of your work. You can save your slide to Microsoft PowerPoint format, as a Quicktime movie, PDF, HTML, image file, or even directly to YouTube.
3. Prezi
   Prezi producing a cloud-based presentation software and storytelling tool for presenting ideas on a virtual canvas, making it possible for users to pan and zoom, and to size, rotate, or edit an object. You can create a more cinematic and engaging experience and lead your audience down a path of discovery. Customers who use the free license must publish their work on the Prezi.com website, which is publicly viewable. Customers who purchase a Prezi Enjoy or Prezi Pro can make their presentations privately.
4. Brainshark
   Brainshark lets users create, share and track online video presentations that can be viewed at any time, on computers, smartphones, and tablet computers. They also offers a free version of its software called myBrainshark. Users also can turn presentations into YouTube videos. Brainshark released SlideShark, a mobile app for your iPad and iPhone that lets users properly display PowerPoint presentations on iOS devices, with animations, graphics, fonts, videos and hyperlinks intact.
5. Vuvox
   With Vuvox, you can assemble a slideshow that’s more like a video. You can choose video type styles from spiral to postcards, to a tree format that animate, arrange, and place the media in modern layouts. It is easy to create a slideshow from the latest photos and videos in the news, using any RSS feed. You could make a very modern looking presentation, which will blow the doors off of any Powerpoint.
6. SlideRocket
   SlideRocket is an online presentation platform that lets users create, manage, share and measure presentations. Users can choose a free 14-day trial then determine which plan to subscribe to. Users also can use a basic version of the software that is free.

Article by Effi, GraphicPanic.com