One app that is also interesting for making passive money is honeygain. It uses your unused GB. In fact it is some sort of mining, but it works slightly different.
They are legit and paying, but it will only give you a few bucks per month.
@BitcoinYu, maybe you could add this app to your list.
Yes the Bitcoin app is usually at the top of the market This is why it is possible to make more money by investing in it than other applications and GB is very low cost. But before that you need to know about the Bitcoin app.