Hope this isn't too rambling as it is my first shot at a bonified theory!

The others are time travelers. They are from the future. Advancements in technology (started on the island in the 1960's) have created a future society where all life is engineered in a lab and not biologically anymore. Due to their advancements in life extension, and being able to create genetically engineered humans without illness....medical science is viewed as archaic and was abandoned years ago.
Something occurred in the future, a flaw in their genetic engineering that only revealed itself after several generations. They are becoming sick, infected and dying at a phenomenal rate. They no longer have the ability to reproduce naturally because they have eliminated it during the genetic engineering as another obsolete function.Their existance is in danger and their only hope for survival is to travel back in time to the place where it all started and correct the mistake. The only open door for them to travel through was created on the island by the magnetic anomaly that has occurred there. (similar to a stargate) They know everything about the survivors because they are able to still receive information from the futureworld who keeps them updated by searching the archives. The information Juliet had about Jack was all matters that would be on record. Graduated earliest in class, top physician, fathers autopsy report. Also,Remember when Hurley and Saiid heard the old music on the radio one night? Maybe the door was open breifly as someone was travelling through.
Another thought, maybe the smoke monster is really a time traveler is hyper speed mode. He is examining the survivors, trying to influence some...such as Locke.
Desmond went through the door by accident. How far he went into the future we do not know. Now he is trying to change events (such as the lightning strike) without direct interference or changing too much so as to create a bigger issue in the future. The others are bound to the same laws of time travel, they must try to change things but not to the degree that they eliminate themselves from the future.
I also think that possibly more than one group of the travellers exist. They are in opposition to each other, there is a battle going on. One group believes in changing the future through manipulation of events.They consider them selves the "good guys" as Benjamin likes to say. The other group believes you simply capture humans and children and bring them back to the future for experimentation and possible procreation of the race again.
So, those are my thoughts and theories after last nights show...now my head hurts....lol.

Yeah,my head hurts too..I think Des is about 2 hours ahead..what do you think..?

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Two steps ahead of the guys with the butterfly nets!!

I am not sure how far ahead Desmond went into the future, but I suspect we will find out in the next few episodes.

Not a bad theory, I can't think of a lot of arguments, except that it's LOST, and so the answer is never as complicated or as simple as we can suppose it to be!

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"The Naked Gun!"

Frank Drebin remembers a lost love.

Frank: It's the same old story. Boy finds girl, boy loses girl, girl finds boy, boy forgets girl, boy remembers girl, girls dies in a tragic blimp accident over the Orange Bowl on New Year's Day.

Jane: Goodyear?

Frank: No, the worst.

I still have not quite figured out the numbers yet and how they fit in. But, they could reference dates....2004,(when our crash occurred), 2008 etc....
I am also thinking that if the others are time travelers they could manipulate a chain of events to get certain people on a plane they know is going to crash on thier island. Such as a spinal surgeon that they need. Also, it seems to me that many of the main characters have come to a desperate point in life... a crossroads. Maybe headed for self destruction, in need of a new start. Also, most of them do not have any strong ties to the outside world. No one who is searching desperately for them........

If that is true, that may well be their own undoing.

Desmond does have someone desperately searching for him - Penelope. She has financial and apparently high-tech support working for her, I believe because she is aware of her father's involvement in some weird Island years ago. I think she knows or suspects that her father sent Desmond there.

Also, I think it's very possible that Mr. Paik, Sun's father, would move heaven and earth to find his daughter, if only to deride her for running away. He might also want to kill Jin for not delivering the watch he was entrusted with. Not so sure about this? Well, if you followed the Lost Experience in the Summer,

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"The Naked Gun!"

Frank Drebin remembers a lost love.

Frank: It's the same old story. Boy finds girl, boy loses girl, girl finds boy, boy forgets girl, boy remembers girl, girls dies in a tragic blimp accident over the Orange Bowl on New Year's Day.

Jane: Goodyear?

Frank: No, the worst.

You make a good point that Desmond does have someone who loves him enough not to give up searching for him. But, he was not a passenger on Oceanic 815 either. As for the Oceanic passengers that are main charachters, it seems that the only people who would still be searching for them more than 2 months later would only be doing so out of some type of ill will. Such as Jin's father in law...he does not seem to be motivated from any type of fatherly love towards his daughter. It seemed to me that he viewed her more like a valuable posession of his. If he were moving heaven and earth to find them I think it would be more like a mob boss/ control freak seeking vengeance. If he thought they had tried to run off and escape him, he would never give up looking, but if he truly thought their plane had gone down and they had perished......I think he would move on pretty quickly. I would have thought Hurley the multi millionaire would have caused a massive search, but how many people might benefit from his money if he were declared legally dead?
I have not kept up with the other items you mentioned, but I found the information quite interesting and it might play into a future world calamity, or a form warfare that could be effective against people who no longer utilized medical science. Could a sought after "code" be a genetic code?

True, but I don't think it's specifically about the Losties who crashed in the plane, but all the scattered apparent survivors who seem to be cohabiting the Island. And that, as we learned tonight, nothing happens by accident on the Island.

Ben finds out he has spinal cancer. A skilled cancer surgeon who once healed a woman - as if by magic - arrives on the Island two days later.


Yes, absolutely it could mean that, and probably it does!

__________________
"The Naked Gun!"

Frank Drebin remembers a lost love.

Frank: It's the same old story. Boy finds girl, boy loses girl, girl finds boy, boy forgets girl, boy remembers girl, girls dies in a tragic blimp accident over the Orange Bowl on New Year's Day.

Jane: Goodyear?

Frank: No, the worst.

Way to go Frogmeister, I like this theory, very much...
From what I gather out of the Lost Experience,

With that in mind, your theory becomes even more interesting. The others may have figured out how to change one of the variables in the future, maybe too late, and have gone back to change it earlier...
Good theory, very mind-twisty, i like that