We don't know who many of the Ajah heads are. In fact, we know for certain of only four in the Tower (the Brown, White, Red and Yellow Ajah heads) and one in Salidar (Myrelle is the Green Ajah head.)
However, I believe that Aeldene Stonebridge is the head of the Blue Ajah.
1) She was VERY angry with Siuan when Siuan revealed she (Aeldene) was the head of the Blue eyes-and-ears. To quote, she "not only snatched control of the Blue eyes-and-ears back off Siuan, she upbraided her in a voice half the village could hear" (TFOH.)
2) The focus of the Blue Ajah is causes. For this, it needs to gather information quickly and accurately, and as the Ajah in itself has no specific cause, its primary function must be to get information that the sisters can use to further the causes they are working on. So, for the Blue Ajah head, controlling the eyes-and-ears is integral to the Ajah function.
3) Therefore, it is reasonable to suggest that in the Blue Ajah, the functions of head of eyes-and-ears and head of the Ajah are synonymous. This explains Aeldene's extreme anger at Siuan - Siuan had revealed something NOONE outside the Ajah was supposed to know. RJ has emphasized how closely that secret is held several times.
Alternatively, the mentions of Aeldene's temper could explain this, but Aes Sedai do not often show anger when a whole lot of servants and others can hear. This would be very unusual. It can also be argued that, as Amyrlin, Siuan should not have know who the head of her former Ajah was, but I think that in fact the Amyrlin seat would have to know who the heads of all the Ajahs (except the Black 
) were.
Also, I think that Morvrin, Beonin and Carlinya may be the heads of their respective Ajahs in Salidar. (Morvrin could be on the Brown council or the council head.) Along with Myrelle, Shriam and Anaiya they controlled Salidar. The heads of four Ajahs and a former Mistress of Novices could exert this kind of power. Anaiya or Sheriam could be the head of the Blues but this simply seems unlikely, as Sheriam was the Mistress of Novices and Anaiya does not seem to have that kind of influence.
Burr says: You make a good point that information management may be one of the most important functions relied upon by the Blue Ajah. However, I don't think that would make a separate head of eyes-and-ears any less necessary. The Keeper of the Chronicles and the Amyrlin do many of the same tasks, for instance, but that doesn't make the Keeper any less needed; because the Amyrlin is only one person. And in the Blue Ajah's case, I think a head of eyes-and-ears separate from the head of the Ajah would be even more necessary than in other Ajahs, since there would probably be so much more information to handle.
Comments
If your theory is correct, Siuan would be the head of the Blue Ajah before becoming Amyrlin. Since we never heard this from her point of view EVER, I think it highly unlikely.
The two positions are separate; they have to be. No other Ajah requires its head to maintain its eyes-and-ears as well, and the Blues have a LARGER network.
Thus, Aeldene is not the head of the Ajah, only the Blue Ajah equivalent to Sebban Balwer.
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But Id agree wih you on Carlinya, Morvin and Beonin being the heads of their Ajahs. I would put Anaiya as head of the blue Ajah. You say that she doesnt have that kind of power but then why would that group be described as being the real power in Salidar? I say that each is the head of their respective Ajahs wth the exception of Sheriam, who previously was Mistress of Novices and a very close friend of Suian. That and her strength in the power is why she has power and is not head of an Ajah.
That still leaves the Yellow Ajah. We know that the yellow leader is in the Tower, but I would put Nisao or Dagdara as head of the Yellows in Salidar. I seem to remember that Nisao was very important among the Yellows, but also it says that Dagdara knew twice as much about Healing as the other sisters in Salidar. Neither is a Sitter so it would be believable that one of them heads the Yellows.
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I know this is a not evry important and possibly untrue theory, but I thought it was worth sending in. I would like to stop and give credir here to someone most of you will not remember, Birdhead, who frequented the MB until a month or so ago. It was her idea originally, but she can't come for I while, so I sent it in.
If Nisao is the head of the Yellows, then why does Romanda go her own way so often? If she is, she(Nisao) is oath-sworn to obey Egwene, so couldn't Egwene get her to rein in Romanda a little, and Anaiya Lelaine? I know Romanda and Lelaine are well respected, but they might obey their Ajah heads. Or maybe Egwene doesn't know who the Ajah heads are, and this will be revealed in the next book and is a part of the plotline.....or maybe not. If it was, that's be one puzzle as to what's in Book 10 sorted. Ah, I'm just dreaming. But who knows? Aeldene may be the head, she may not be. Time - or maybe RAFO - might tell. We hope.
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The likely heads of the Yellow and Blue Ajahs are Romanda and Lelaine, respectively. Even if they don't hold those positions formally, they have the authority of them.
The likely head of the White Ajah is the Sitter Aledrin. Aledrin is the youngest White Sitter, and authority in the Hall goes by age; yet Aledrin, when standing to declare war on Elaida, pulls the older Berana to vote with her. Since she doesn't have authority by age over Berana, she must have some other form of authority. Most likely, that of Ajah head.
Granted, Lelaine is the strongest blue in Salidar and together with Romanda she quashed Sheriam's faction's influence in the hall but if she was head of the blue ajah then why don't Sheriam and Anaiya give up their up their goals in favour of Lelaine's. Aeldene is the head of the blue's network but she does not have any influence over Sheriam, Anaiya or Lelaine that we have seen so far. She has tried to get the amyrilin's network out of Siuan but Siuan has resisted her so far. As regards Lelaine, she did not support Egwene's declaration of war against Elaida until Moria attacked her and even then all she warned Moria with was a talk of proper protocol. I believe Moria made a mistake in attacking a sister who is older and stronger than her but that is it. Also Siuan would have told Egwene if either Lelaine or Aeldene leads the blue ajah, she has already proven by her past actions with Moiraine, that her main loyalty is to seeing the Dark One defeated and not to the blue ajah or to Aes Sedai in general. The true head of the blue ajah remains to be seen.
or, in fact, you truly ARE an utter moron.
This is a theory post. This is a theory on the theory post. The theory states what people think is going to happen.
Now, I personally don't much care about this particular topic. However, one theory poster and 5 posters above you have already expressed an interest in the subject. THEY care.
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Siuan was not the head of the Blue Ajah