I'm not sure if anyone remembers the Microsoft Courier tablet demo, which came out before iPad's announcement:

http://www.youtube.com/watch?v=UmIgNfp-MdI

This video left me with a strong impression of future general computing usage patterns. It has also been my personal gold standard of a superb video demo.

Interestingly enough, they abandoned it right after iPad's release:

http://en.wikipedia.org/wiki/Microsoft_Courier#End_of_Courie...