As you progress in the game you receive various rewards. Generally speaking, they serve no purpose apart from decorating your hideouts. You have to have them if you want to finish Chinatown Wars in 100%, though. Below you have a list of these items along with short descriptions how to get them:
Jeweled Key to the City
Come into possession of all 21 hideouts (the map as well as the descriptions of the estates can be found in a chapter entitled 'Hideouts, Scratch Cards, Stations and Shops').
Track and talk to (or make a transaction with) forty drug dealers (the 'Drugs' chapter contains a map with their locations).
Track all eighty drug dealers (again, familiarize yourself with the 'Drugs' chapter).
You win it after earning your first $2,000.
You get the spoon when you make a $500 loss on a drug transaction. It may be problematic to find such an unprofitable offer among the traffickers. Head to the hang-out of a drug-dealing gang ('Drugs' chapter) and buy as much of the substance as possible. Then sell it back to the same trafficker or to one of his friends. After that you should be out of pocket.
The Jeweled Bong
Reward for distributing weed and downers.
Reward for trafficking in ecstasy and acid.
Reward for coke and heroin distribution.