Cuculcan is a collaborative timeline editing and sharing service. Think of it as Wikipedia for timelines. Anyone can create an event or timeline and anyone can edit those events and timelines. You can can search for timelines and events and you can compare timelines.
Or at least, that’s the eventual goal of Cuculcan; it’s still in development.
Oh, if you’re wondering about the name, it comes from Kukulkan, the Mayan snake deity also called the Plumed Serpent or Feathered Serpent and known to the Aztecs as Quetzalcoatl. Three K’s in a word, however, seemed problematic and thus Cuculcan. The picture here shows the serpent, represented as a shadow, descending the staircase at El Castillo at Chichen Itza on the spring equinox.