It's cool that ACNs can get two jobs, and I think I remember it being said they were thinking of doing that for other classes. Just figure I'd jot down ideas for 2nd jobs for other classes.

Maraduer - WAR is the tank version
Samurai would be a DPS version

Gladiator - PLD would be the tank version
Dark Knight would be DPS version

Archer - Bard
Corsair One would be a dps with some buffing ability, other would either be a buffer with some dps ability, or maybe a dps with some debuffing ability.

Pugilist - Monk DPS class
Thief or Ninja would be a DPS class through DoTs and debuffer.

Lancer......i'm having trouble thinking of an alternate.

Conjurer - WHM is healer
Geomancer would be dps version

Thaumaturge - BLM is dps
Red Mage ...I don't know but I want one so there.

I dunno. Just wanted to throw it out there.