I just tested 280 Slides and I am kind of impressed how comfortably you can create simple screen presentations without having to use an installed tool like OOo Impress or MS Powerpoint. It's got a nice GUI like Apple Keynote and offers basic tools like inserting pictures or movie clips.
But I also have to admit, that I did not try Google apps or similar services yet.
At 280 Slides, you can download your presentation in the MS Office 2007 format pptx
. So you have got at least something in case the services goes down.
Note: this blog entry was originally authored using Serendipity and converted to Org-mode format for publicvoit via a dumb script. This may result in bad format or even lost content. Please write a comment if you want to get in touch with me so that I can try to fix things.