I am actually going to play strictly to the rules and only pick ONE movie per slot (e.g. I won't be cheating and mentioning the whole Harry Potter series, for example.) Most of my selections are geeky, but a couple of them are not (gasp).
Without further ado, here are my favourites:
10. The Italian Job
A clever heist, good acting, and car chases that are actually interesting. This movie is fun, and even appealing to the non-geek.
9. Pride and Prejudice
What? A girly movie on my list? Come on, I think I'm entitled to at least one... And yes, it's the long BBC version.

8. The 10th Kingdom
No one seems to have heard of this movie, but it's so good! A fantastic twist on the "lonely lass finds her way into fairy-tale land" story. It's so much fun. I might have to write a review on it to further convince you all.

7. Spirited Away
Miyazaki's finest. So weird and so good.

6. Back to the Future
A classic.

5. The Avengers
Joss Whedon can do no wrong, can he?
4. Sword in the Stone
My favourite Disney movie. My family can quote this one backwards and forwards.

3. Serenity
What was I saying about Joss Whedon? So glad Firefly got a movie that tied some of the loose ends. And it's a fantastic movie even on its own.

2. Empire Strikes Back
The original trilogy is still the best. I like to pretend episodes I-III don't exist. Episode V is my favourite.

1. The Fellowship of the Ring
I was brought up on Lord of the Rings. It was so exciting when this came out, and it absolutely didn't disappoint. It's my favourite of the trilogy.
And there you have it. Whew. So hard to pick just 10. Honorable mentions go to Doctor Horrible's Sing-Along Blog, Harry Potter and the Chamber of Secrets, X-Men 2, and Tangled.
What are your top ten movies? Be sure to stop by Alex's blog and visit the other participants in the fest!