Was just randomly thinking about how many times the dragon's been broken thus far.

So far I've got, in no particular order:

Events of the Battle of Red Mountain (Numidium, apotheosis of the Tribunal)

The Time-Wound on Snow-Throat

Activation of Numidium by Tiber Septim

Activation of Numidium in the Warp in the West

Return of Ysgramor

Pelinal Whitestrake

The Maruhkati's Dance on the Tower

Defeat of Alduin (a literal Dragon-Break)

Auriel's dracochrysalis (I'm assuming that's the dragon-break that Mannimarco mentions in "Where were you when the dragon broke")

Am I missing anything? I was wondering if other events also counted as dragon-breaks, like Martin becoming the Avatar of Akatosh, or Alinor's Mirror-Logicians continuing defense against Numidium?

Neither Pelinal nor Ysgramor count as DB's, and the time wound on High Hrothgar is another thing entirely (it's persistent, for one). Alduin's defeat isn't really one either, since we're not talking about the same time dragon.