OMG is this really the end, oh crap no not yet, sit back down.

For me it was when they arrive at Minas Morgul, that part came closest to the feeling I had from the book. And the whole extended version, which made it a lot better.
I had many OMG moments listening to the 13 hour commentary track on the extended blu-ray edition, one of the best commentary tracks and very interesting to hear how everything was put together.

Obviously seeing the Balrog and Gandalf's "you cannot pass!".
(well, not "obviously" after all because the movies have many other amazing OMG moments).

There were a shit ton in 2 and 3 some in the first but the hobbit series is way too unbearable

MY OMG is how bad the Hobbit was. Smaug was better though

My "OMG" moment in the LoTR trilogy was every second.
My "OMG" moment in The Hobbit was how good it actually was compared to what people were saying about it.

Haven't seen it, I hate cinemas. Going to wait for it to come out on bluray. My omg moment is going to be when Legolas first appears. He's so awesome I'm almost gay for him.

Charge of the Rohirrim at the Pelennor Fields.

Probably the greatest moment in cinematic history.

Oh God, so many...

Fellowship of the Ring:

- The fight in Balin's Tomb

- The collapsing stairs just after that

- Boromir's last stand and death

Two Towers:

- Gandalf fighting the Balrog in midair as they freefall down a chasm into an underground lake

- The Ents destroying Isengard

Return of the King:

- Faramir's suicidal ride to take Osgiliath while his father calmly eats lunch

- The Mumak (giant elephants) showing up when the battle seemed to be won, and decimating the Rohirrim

- "I can't carry it for you... but I can carry you!"

The Hobbit Part 1:

- The dragon attack. Such a great sense of power and danger.

When the Shire legally recognized gay marriage so Frodo and Sam could finally stop living a lie.

Actually, this is mine:
http://au.news.yahoo.com/a/20440631/polish-pranksters-stop-tram-to-film-Tolkein-scene/