Nice. Here are a few triggers/events I'd like to see:
( Of course you can think of more

)
Triggers: IF (trigger1) AND (trigger2)
IF (trigger1) OR (trigger2)
Planet first sighted in sensor range
Planet settled
Star conquered
Star destroyed (through death star)
Ship named X destroyed
Ship named X reaches level Y
Race X discovers Tech Y
Declaration of war/alliance/peace between X and Y
Module of type X added to starbase near one of star (in sector?) of race Y
Events: Cause/Break alliance between X and Y (this combined with preceding triggers would let modders fix some diplomacis issues in Galciv so you wouldn't have to code them yourselves)
Declare war between X and Y
Destroy civilisation
Spawn (minor?) civilisation (spawning a major would be fun too - here come the Drengins!)
Give planet/star system to civilisation X
Give new ship(s) to civ X in sector Y (important: precise only sector or give several possible spawning locations so they don't start in the same place as enemy ships)
Create/Destroy star system/planet (adding planet to an existing system would be cool - allow to do some stuff with planetary creation techs: you could build a starbase, add a module requiring planetary creation tech and spawn a planet or star system in place of the starbase)
Change PQ of planet X or of planet nearest to square X (increment/decrement or +%)
Spawn/Destroy resource
(Most important) Show panel with text - allowing to play a video of some kind or display an image would be great too
Run a specific 'random' event (with all the moral choices and effects associated)
I can think of more if you like

Note that I'd really like events to be able to maniuplate not only the player but also the ai's, so for instance if terrans attack Drengins, then Yors decide to attack Drengins too even if they are not allied with Terrans (but they smell blood) (or they attack Terrans...)