presentation

Firstly, it's worth nothing that Powerpoint is not the only option for creating presentations and whereas Powerpoint costs hundreds of dollars to legally purchase, some other optoins are free.

• Google Docs -  free to use with your gmail account. Much simpler and less sophisticated than Powerpoint, but makes it very easy to collaborate and publish online.You can upload save file as a ppt or pdf for offline usage and also upload ppt files you're already created with Powerpoint. (Google Presentation Guide here)
• Impress - is part of the OpenOffice package which is free and includes alternatives for MS Word and Excel as well. It's very similar  to Powrpoint, but a bit simpler to use and less sophisticated in its options.
• Prezi is also a cool new way to create presentations and publish them online if you wish.
  You can link to any of these presentations or embed them on your website. Some presentations from Prezi, Slideshare and Authorstream can also be downloaded, but you'll need to create an account with each in order to do so.  Presentations made with Google Docs can also be downloaded, but there is no directory listing the Google Presentations.  People just post them on their own sites. 

There are also a number of sites that allow people to upload their presentations so that other people can view (and sometimes download) them. Some of these are:

• Slideshare - largest collection of online presentations. Also includes 'slidecasts', audio narraated presendations
• Authorstream - also includes the option for users to include audio narration
• Voicethread - includes the option for viewers to respond to presentations with text, audio or video.
•  Here are some specific examples:
  
  • Negative Questions (Authorstream)
  • Conditions for Optimal Language Learning (VoiceThread)
  • Synchronous Communication Tools in EFL Online Learning in China (Slideshare)
  • Simple Past -ed Pronunciation (Authorstream)
  • Stylistic Classification of English Vocabulary (Slideshare)
  • Practice Your English (VoiceThread)
  • History of English (Prezi)
  • Gangs of Korea  (Prezi)
  • Storytelling Techniques Explained (Prezi)
  You can also search through thousands of other presentations on these sites.  Here are links to presentations tagged with EFL or ESL

Slideshare  search   EFL and ESL
Authorstream search  EFL and ESL
VoiceThread  ESL   EFL
You can also search through these sites using specific terms like 'english grammar' or 'efl education