Anyone have any ideas on what that thing is?

http://lost.cubit.net/indexView.php?id=498 has some speculation on its possible ability to shapeshift into people from the characters past (which would explain all the suddenly disappearing dead people, and also on it maybe being called Cerberus and the significance thereof

Actually, more and more it looks as though they're dead but don't know it yet.. but I'm sure that's been specifically refuted in an interview 

That's what I thought the smoke monster was, but they stopped focusing on it and then it came back to kill someone and they didn't mention it again

I'm thinking it's the creators' back-up plan for dealing with contract terminations 

I think Jakob has something to do with it.

If I remember correctly it has been stated by the producers that they aren't dead

hang on fellas... is that smoke monster an actual monster or one of those "inner deamons" kind of thing?? 

I'm fairly sure it's an actual monster

It killed Mr Eko, never seen a psychological quirk do that

Yeah, exactly..

I miss Eko.... I liked him 

yeah, Eko was pretty cool

his back story made for some interesting watching too 

Yeah! Exactly!

And I thought he'd have been good for a fight scene or two 

he seemed a little too spiritual for that to me.. maybe if he was pushed far enough though - he has violence in his background and he's not ashamed of it

yeah...

When Kate and Juliette are running trying to get back to camp, the smoke monster appears, and perhaps it was just me, but it seemed that the smoke monster appears most often when there is "fighting" or raised voices... *shrug* Just something that caught my eye in that episode... there is probably no correlation between the monster and "fights" but.. it sounded plausible to me.

 Edit: 

A friend, and fellow LOST fan pointed out a number of problems with my Monster=comes around during fights theory...

Eko was alone when the Smoke Monster killed him... and the co-pilot wasn't fighting with anyone when he is snatched out of the plane by the Monster.

i remember it appearing when someone is just standing there.... tho i might be wrong...

If that is the case, it's an interesting element..... maybe it's their own wrath! 

It does have a habit of interrupting tense moments to force 2 conflicting characters to cooperate briefly

But it also comes out of nowhere, at random, to people who are on their own and other non-conflict situations, so its either unrelated to conflict, or the writers are really inconistent, or its an occasional plot device to get  2 conflicting characters to cooperate briefly

hmmmm.....