Cheat codes:

During play, press Ctrl+Alt+C and enter the codes.

Dealian Treasury    Get 5000 cash
Gimme Goods         Get free goods in warehouse/mill  
IgnoreDesire        Houses evolve without needing desireability   
I win again         Win mission at end of month  
Uncle Sam           Tax collectors change into Uncle Sam  
Glub Glub           Flood 
Great Heat          Drought 
Shake Shake         Earthquake 
Black Death         Kills all military units  
Kill Enemy Units    Kills all enemy military units  
Kill Loan Units     Kills all loaned military units  
CeramicsForElite    Every Elite house gets 100 units of ceramics  
FunForElite         Elite houses evolve without entertainment  
HempForElite        Every Elite house gets 100 units of hemp  
SilkForElite        Every Elite house gets 100 units of silk  
TeaForElite         Every Elite house gets 100 units of tea  
WaresForElite       Every Elite house gets 100 units of bronzeware/lacquerware  
Bad Wallpaper       All buildings become inauspicious
Chinese Flu         One house becomes infected with disease  
SpawnMugger         One mugger is spawned  
SpawnBandit         One bandit is spawned  

Thanks to Revolution readers Tobias Engström and Martin Brodeur!