- I can make them, in a browser, from anywhere. You can see them, in a browser, from anywhere.
- Sharing. I can co-build a presentation.
- I don't need to carry them around. I can walk in, connect someone else's box to a projector, and show my presentation from the web.
- I can embed presentations in a web page.
I just created the presentation, clicked on Publish, and cut-and-pasted the HTML it gave me.
If someone reading this knows how to do this with spreadsheets, tell me.