I put this in because some of us hate getting random types of girls, and some, like me, like to have a brothel with certain types of girls (one for large breasts, one for monster girls, etc.)
So I would like to put forward the idea of using an item as a catalyst to help you find a certain type of girl, in order to keep it simple I think the easiest way to do this would be the use of keys, simply being, if the character possesses a key, the chances your gang will find a girl related to that key will be increased.
Also, thinking along those lines, a lockpick, if the player is in possession of a lockpick, kidnappings for all girls will increase.
Since these items help with illegal activities I think it would be appropriate to make it where if the player gets busted with the keys\lockpicks then he has to pay a fine, equal to say, 10% of whatever he has on him. Minus 1% for every 10% of influence with the mayor.
hopefully I havent mixed up the games I was playing similar to this one
anyways, tell me what you think
edit: What I mean by related is that you can have things like, house keys, church keys, brothel keys, bar keys (they have inns on the 2nd floor usually, women found here would most likely be strong-willed and disobedient)