So, how about that 100th episode?
It's pretty much a textbook example of a whole mess of fan pandering, but dammit, they made it work. It was fun and clever and featured what was actually the right balance of that aforementioned pandering and some real surprise directions. Not to mention it had a genuinely solid ending built on appreciating the little background world the show has built up over time (a lot of which existed mostly in the heads of Bronies until now, so seeing that recognized felt even nicer).
Also, was not expecting the return of the Lebowski ponies, which, much like the rest of the episode, walked that fine line between too much and just right, and it worked wonderfully. A shame that the Walter pony didn't talk, but then, I can't imagine him saying anything that would be permissible on the episode anyway (also: he rolled on a Saturday! All kinds of wrong, that).