Sorry, one more:
My first Century ride, despite a broken Schlumpf hub at mile 76, 2011
Riding my geared unicycle with smooth shifts 95% of the time. Next would be the four mountain bikers I passed last week while climbing a steep dirt road. When they saw that I was older, a woman, and on one wheel, their faces were crest fallen. It was kind of poetic (and very rare).
When i got 100cm sidehop i was shaking and full of energy for a couple days i was so happy.Another greatest moment was coming 3rd at unicon trials and the feeling i got when it finished
When I rode the steep downramp on the Maple syrup structure at Woodhill MTB park. I am sooooooo happy I did that, I got such a buzz of adrenaline after doing it 
Im the second unicyclist to do that I have wanted to do it for ages but have never had the guts till lately.
It would be way back when I was learning and l rode away from the wall for the first time and realised I could actually ride a unicycle.
It was only a short distance but the sense of achievement was amazing.
I have to add my first unispin in, just did it this Monday. and the Fattire Challenge. and learning how to ride.