Episode 13 of Aria the Origination. Concluded my #1 anime of all time with the best possible expectation-fulfilled
Episode...... errr, which episode was it again... anyway, the episode from Baka to Test to Shoukanjuu, where Akihisa's three great pencils came on screen. (Problem Breaker seriously made my day rofl'ed =)) )
Full Metal Panic Fummoffu, again I don't remember the # of episode it was. Actually there ARE (yes, are not were xD) 2 episodes. One about the rugby club. And the other one is about that 'deadly' bacteria
Higurashi no Naku Koro ni episode 4. When Keiichi died on such a place. It gave me the chill for real, that time.
Lucky Star episode...!! The point is, the episode where Kuroi-Sensei wrote on her blog, and then when she clicked submit button... (I'm sure anyone who ever watched Lucky Star knows what after the ... xD)
Shakugan no Shana II episode 24. The ending. A good yet 'sad' ending. A sad yet 'satisfying' ending. To add more, [Sense] is definitely one of my most favourite songs of all time.
Seto no Hanayome episode number 26. The last episode (putting aside the OVA) of the best ever comedy type anime I've watched.
Suzumiya Haruhi no Yuutsu 2nd Season episode 9. The arc-breaker episode of endless eight. I'm claiming that it's only me that felt that the eighth episode of endless eight had an awesome "arc-breaking" conclusion. Even myself never understand the exact reason behind it.
To Aru Majutsu no Index episode...... 19 (iirc). Damn, I am curious even to this very second about what was Touma say to made Mikoto blushed
Zero no Tsukaima Futatsuki no Kishi. The episode where Saito bravely (or you might call it foolishly) fought against the whole enemy army, ALONE. And RIP. (correction, he was revived

)