I have written several times in the past about Google Documents and Spreadsheets. It is an excellent free online word processor and spreadsheet. You can find my previous articles at http://tinyurl.com/yolm7r. Now Google has added PowerPoint-compatible presentation to the free office suite. Since the title of "Google Documents and Spreadsheets and Presentations" is a bit of a mouthful, the company has also changed the name of the service. From now on, these free tools will simply be known as "Google Docs."
The new software is multi-user. In fact, multiple collaborators can edit the same presentation at the same time. The software works in all popular web browsers, including Firefox, Opera, Safari and Internet Explorer. You can also upload images and changes backgrounds using the theme selector. When you are done with the presentation, you can choose to save it as a ZIP package for offline archive.
The online documents either may be may be made public or left private and accessible only with a user name and password.
You can try this for yourself at http://docs.google.com. The service is free but you will have to create a user name and password. Use your Gmail user name and password, if you have one. Otherwise, create a new account (which will then become your Gmail account). Once logged in, click on NEW and then click on PRESENTATION.