Haha. Civ V is one of my favorite games.
Discovering Ruins, Natural Wonder, or a city state (as the first one).
Founding a city
Destroying a barbarian encampment. Also puppeting/annexing/razing an enemy city.
Diplomacy: Deannounced, war declared, friend declaration, a trade not accepted.
Learning a new technology
Finishing a Wonder
A Great Person has been born
One of those lists (the ones with the pointiest sticks, and so on) pops up
Worker Captured, or getting hold of one from the barbarians
Choose a social policy
In the beginning of every turn during Golden Age
When happiness reaches 10, 20 and so on
That's all I can thing of from the top of my head