Press the tilde (~) key to bring down the console, and input one of the following:

bestbuy:
Units are 10% cheaper.

jericho:
Walls will crumble.

add_money 20000:
Adds money. X = amount.

add_population Y X:
Adds population, where Y is the settlement name and X the amount.

auto_win attacker/defender:
Attacker or defender automatically wins the next auto resolved battle.

create_unit settlement/charactername unit_ID amount exp/armour/weapon:
Creates a unit in the selected settlement or characters army with the stats you input.

toggle_fow:
Toggles Fog of War

give_trait characternname traitname level:
Gives the character the trait at the chosen level.

list_traits:
Lists all traits.

move_character Z X,Y:
Moves character to location, where Z is character name and X Y are coordinates.

force_diplomacy accept/decline/off:
Forces opponent to accept diplomatic proposal.

invulnerable_general charactername:
General is invulnerable in combat.

season summer/winter:
Changes season.

process_cq "name of settlement":
All building in settlement is completed, this only works on one settlement at a time.