GMail now has an inbuilt PPT viewer that lets you view Powerpoint attachment as a Flash picture slideshow in the web browser itself without requiring Microsoft PowerPoint application.

This slideshow feature of GMail will be useful since you no longer have to download the full PPT attachment in order to view that 16th slide of the presentation.

Here are two additional situations where it may help:

1. If you have to view a presentation on some computer that has no copy of PowerPoint, gmail yourself the PPT file and watch the slides inside the web browser. [similar to