I don't know if it's the Aha moment you are after. But in my programming 101 class the lecturer outlined the maximum-contiguous subsequence problem (which sounds very boring). Solved it once and then solved it two more times each time making it more efficient. That was my 'aha' moment that I decided I wanted to be a programmer.
I suspect that this is the most important learning moment - what is it in programming that excites you? (probably won't be this article :)