With no additional work required, you can earn cash back on your regular purchases by connecting your credit or debit card to these apps. Using lock screen apps, likesatta ling Slidejoy or S'more, which display advertisements or content on your phone's lock screen in exchange for a small payment, is another way to generate passive income through money-making applications. With little work on your part, these apps can be an easy way to supplement your income without interfering with your daily schedule.