I think I would do well if I jumped into any of the Indiana Jonesmovies and was a sidekick or femme fatale. God knows, I’d be better than Kate ‘Screamin’ Capshaw in #2.
Not changing the plot or dialog, just running along with the events as they happen.
If this technology ever happens, I call dibs on this series. 
Other flicks I’d jump into:
Pride and Prejudice ( Colin Firth…ooooooh baby)
Love Actually
About a Boy
Chicago
Star Wars. I’d be happy to just jump in as a random Rebellion or Imperial underling and just live out the rest of my natural life there.
Keeping in mind that it’s way more fun to watch battles and near misses with death, I have to say my movie is Enchanted April. A sweet and gentle story about renewal through love, set in the eye-poppingly gorgeous Portofino area of Italy. If I ever come into flipping great wodges of cash, I’m so buying a villa there.
:geek alert:Anything ** Star Trek**–just to be on the Enterprise–especially ** ST2-TWOK**! Dibs on that series!
:smack:
please insert, “than to experience them firsthand” at the end of that first clause. Sheesh.
LOTR: Return of the King. After all the fightin’ is over and our heroes are settlin’ in.
I’d love to be a stunningly beautiful Elleth (female Elf) that would make Legolas forgtet ALLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL about Gimli . 
Debbie Does Dallas
Oh, c’mon, like nobody else was thinking something like that…
I have a whole list of porn movies I could rattle off! I’d love to co-star in just about anything with Anna Malle, Jeanna Fine, Lisa Lipps, Minka, Asia Carrera, Brittany Andrews, Nici Sterling, Ariana, Summer Cummings, Tianna Lynn…
Get out much?
The Extraordinary World of Zinc.
Mmm… Serenity.
I can easily see a younger version of me as Princess Leia. I have that spunky smartass gal quality, and I look good in earmuff buns. Used to wear my hair that way in the '60s.
Sure I do. What’s your point?
Zinc! Come back, zinc!
A musical, like *Swing Time * or American in Paris. Everyone dresses in gorgeous clothes, knows the words to every song, and dances gracefully at the drop of a hat. Bonus points for Technicolor ballgowns.
Umm… as long as we’re going to be able to jump into fantasy worlds…
I’m going anime, all the way (These are possibilities. If I could jump in, I don’t think I’d leave. So, it’s just one I’d use, not all.):
Patlabor. I’m going to marry Kanuka Clancy.
Nausicaa. I’d want to be Kushana’s lieutenant. That is one seriously bad-ass babe. I’m not sure I’d live through the experience. I don’t know whether Kushana has good long term odds of survival, but I’d be willing to fight for her.
Gundam Zeta. Any of the techie/DC types there. And I’d be trying to keep Emma alive. (C’mon, Camille shouldn’t have to kill all the cool women he meets, dammit.)
Mahou Tsukai Tai. I’ve got that reporter’s role. It’s mine, I tell you. Mine! Mine!!!
Kodomo no Omocha. I’d want to make up some new role here to try to hook up with Mama Kurata. Even if that didn’t work, however, it’s still a fun and cool place to be.
I could think of more, but then people might get the idea I’m obsessed with anime, or something. You know - that I’m some kind of Otaku. Can’t have that happening. 
I think Doc and Marty could’ve used some help in the Back to the Future trilogy. Rachel McAdams could have used a love interest in Red Eye. Okay…she didn’t really need one so much as I want to be one.
Pleasantville
–Cliffy
I think maybe I’d like to jump into an old film noir story and give away the plot. Maybe something like Double Indemnity where I could slap Fred MacMurray in the face and say “The dame’s makin’ a sap outta ya! She’s settin’ ya up for a fall. Wise up!”
You’ve just about paraphrased the game “Star Wars Galaxies” in your one sentence. Everyone complains that it’s not fun because you don’t get to be a Jedi. Instead of Luke, you play the guy who Luke’s uncle takes his speeders to when they break down, that kind of thing. Maybe you oughta look into it.
Anyway, I’d jump into Lord of the Rings. I wanna live in Rivendell.
If the upcoming Narnia movie is any good, though, that might be my #1 choice instead.