For as long as I've been following this show with other fans (I came in before Season 3), I've been able to conceive of theories on many of the mysteries of this series. Now, I don't know what my track record is, but I think I've been doing fairly good. But that's a moot point because this is one oddity that I have not even been able to muster a single idea on. I'm dumbf***ed. But I'm sure that when the issue is addressed to whatever degree, I will be gobsmacked.
A couple of things to note: in his podcast for "Islanded in a Stream of Stars", Ron Moore debunked the Daniel theories. It's unusual, but I think he believes they were getting out of control. I, for one, never really took wanking to the concepts of Number Seven's potential role. I easily accepted the character's note as nothing more than dual execution of both explaining the absence of the number in the sequence of existing Cylon models and providing Cavil with some back story of wickedness. I was surprised to hear Moore illustrate it so close to how I thought of it in his podcast for "No Exit". Amazingly, despite no mention before, or even of anything since, the Daniel notions continued and I'm sure there are some clinging to them even in light of Moore's pardoning it.
Another thing is one of the promotional images that were released for the second "Daybreak" episode that I added to its gallery. In one of them (the 7th), you can see Adama, Caprica-Six, and Baltar taking note of some unidentified person in the foreground. Even though there are no clearly indicators, the shape of their head and hair makes me think it's Kara. Certainly not the one we've been following throughout Season 4 nor the one who took a nosedive into the dense, bone-crushing heart of a gas giant and wound up a charred corpse on Earth (assuming they're the same people, mind you). The simultaneous confused, shocked, and fearful looks on Six's and Baltar's faces would fit into such a revelation.
I will say that some theories that have been floating around make me wonder if people are really paying attention to this show. To me, the concept of she being a Cyclone (let that sink in), is kind of clichéd and doesn't follow the reality of this show. Whatever she is, I'm sure it's deeply rooted in something very spiritual. It has to be connected to the journeys Number Three took (there's even a fairly verbatim description used for both she and Kara's trips to the brink of death), which, of course, is tied into the Final Five - which is furthered when you realise that she popped up in the Ionian nebula the point in which their musical trigger hit its zenith. Then, of course, "Someone to Watch Over Me" tied Hera into all of this. She's connected to the Cylons, but I don't think it's as superficial or technical as so many are putting it out there to be.