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iPhone. Especially the Conference calling, Pinch, Accelerometer, Coverflow & Visual Voicemail demos.

A close second would be the iMac G4 announcement, especially the part where he demonstrates the LCD movements. Its still the best designed iMac to date IMHO.

I occasionally go back to watch the announcement keynotes of these products
 
I still like the first Mac and the Lisa -- huge chance in how things were done.

And the NeXT OS was the next big step ... though Apple bought there way into that.
 
Having made the jump from a personally owned LC (my only mac at the time) to a 6220cd Performa at school, I was blown away by the B&W G3 Tower. At the time, going from my home LC (and Pentium 166 PC), it was a rocket ship of a system.

I wasn't able to afford my own until 3 years later, however this system is still functioning and only lightly tuned up (G4 - 500 Mhz), is still a viable system on my network, serving up Audio / Video, and used as an internet workstation!
 
The original Titanium Powerbook.

I bought one the week it was released. I knew as soon as the release happened that this was how a laptop should look and work. Every Powerbook and MacBook Pro since has just been a refined version of that design.

Mine was early so I got the standard flaws - the paint chipped and the battery latch broke several times and the frame buckled a little and the hinge broke big time and it came with OS9 - but I still loved it.

It gave me 5 years of faithful computing, the battery lasted 6 hours of researching in the State Library here in Sydney (I was doing my BA in history at the time), I got to try networking with another student using IrDA (a technology that deserved to die!) and I got incredible amounts of envious looks at Uni and out on the street. :)

Oh, and I got to watch DVD on a great LCD - very cool stuff at that time! Of course, I did once spill a bourbon & coke through the whole machine when the interstate train I was on lurched as I raised my cup....

To top it all off, the machine is still doing sterling service for my father as his desktop. Even though the busted hinge means the screen can't close & it only has a 40GB HDD and 512Mb RAM, he happily checks his email & surfs the web on it every day. The only thing he doesn't like about it is that he can't load Google Earth!
 
iMac G4.

I only bought my G3 a few months earlier and if I knew this was comming I would have waited. I never owned one but some time ago I did a clean install of one for a friend so it was standing on my desk for a few days, I still want it beck there. Even more, it was in mint condition.

As a matter of fact all my macs were exciting, even my beige LC and my performa 5200.
 
When one of the PC magazines rated the MacBook Pro as the best and fastest laptop for running Windows (can't remember was it for XP or Visa) but the benchmarks we're definitely on the MBP's side... I guess, when they announced that, loads of PC users found themselves buying Mac.

Makes a refreshing change, doesn't it? :D
 
For me it was when I first saw the first generation Nano. I couldn't put my mind around how small it was. Of course the iPhone was amazing but we all knew it was due to come at some point.
 
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