I've received some really great gifts over the years, but the one that stands out in my memory as the most exciting was (and I'm exposing myself as a huge geek here) the Apple IIe my parents bought for me and my sister when I was in sixth grade. Up until then I had been using an old typewriter with a sticky "e" to write my stories about ponies and princesses; Bank Street Writer opened up a whole new world of word processing to me. (I might have played a few games on it, too...but they were educational!)
Of course, since then I have upgraded computers a few times, and the old IIe was eventually donated to charity---and with it, all of my old stories, which, in their disappearance, have become totally legendary in my memory. But I can still remember that feeling of excitement Christmas morning. The boxes were so big! And numerous! And it took the entire day for us to get it set up and running! No gift I've yet received as an adult could quite compare to that...although for the record, I'm not adverse to people giving it their best shot.