Just scanning through the thread I missed any SMAC achievements so I thought of some, including others:
Alpha Centaurus: Start as horse people and name your homeworld planet.
We must dissent: Meet a fanatical spirutualist fallen empire
Breaking the Charter: As the humans, use a nuclear weapon
Molon Labe: as a militaristic empire, get attacked by a fallen empire
You begin by carrying away small stones: (Re)move a mountain
For the greater good: As fantatical collectivists, conquer the galaxy
Cradle of the mind: Colonise a new planet
99 planets but a beach ain't one: Control 99 non Ocean and non continental planets
Grand army of the republic: Start on a ocean world as a non-direct democracy, and discover cloning
Roger roger: Lose a battle with a synthetic army
Sent in the next wave: Lose a ground invasion, but still conquer the planet within the next in game week
No bugs, only features: Exterminate all insect races in the galaxy
Millenium Falcon: When you have researched the best engine, still have a ship that is using the first engine
Sorry if others already gave these suggestions
EDIT:
Battlestar: Crush an AI rebellion with just one battleship