Another way to make money is by investing in companies. Have a look on the computers in the police department, in your house, in the sex shops,... to see how the stocks of different companies are going, if you feel that the time is there to invest in a certain company, then buy some stocks and check after some hours how they are changing.
You might either lose money, or make money from it. If you feel like your company is about to lose money, better play safe and take your money back by selling the stocks.