I don't know if this is common knowledge or not but...
The Orderealm quest in which Mavado offers you 500 koins for 1000 rubies is quite beneficial. I am on my second run through Konquest and I have just come to Edinia in the main Quest. I went back to Orderealm and for some reason felt compelled to talk to Mavado. And he once again tol me verbatim "It was a pleasure doing business with you. Please to not tell anyone that you have see me here." and he gave me 500 Sapphire koins again... and again... and again... and again each time I talk to him in D-5 of Orderealm. I'm playin XBox so let me know if you all get the same result on other systems.
Oh ya, and does anyone know about the second Quest Shao Kahn gives you about Reiko liking to wear his helmet and to ask him to stop?
Sorry if either of these have already been discussed but I just joined this and other boards a couple of days ago and have based all my secrets and quests from the "Konquest Mode FAQ" on gamefaqs.com.
Hope this helps y'all... enjoy