You can make money from your Android phones. Depending on the type of app that you are going to use the money that you earn will surely vary.
This app is on invite basis these days. And it allows you to do trivia, puzzles, video watching and app locking. So using these features you can earn some points. And you can make some good vouchers to the Dominos McDonalds etc. It also has the PayPal withdraw option. Do note that it's not easy to reach withdrawal here but once earned you can either get a cash or voucher for it. It's a very popular app these days as it's easy to earn points but harder to reach the point where you can make withdrawals.
This app requires you to install other apps. And you earn some points from it. And once you reach some specific set of points then you can withdraw for the cash in PayPal. It's easy to earn points by installing other points. But your phone or tablet gets cluttered. And this means you need to use your spare phone for the same. You also require a lot of space for making money by installing apps. But it can earn 5$ or around just fine.
This app is basically an app locker. So it locks the smartphone and shows ads before opening the lock. It means you may have to use this app on regular basis and while connected to internet. This way you can easily earn some money. Though don't expect to get paid more than 5$ from such apps.
I use this app to post my images. And then if someone buys photos from my account, then I get paid. This also helps when I want to make money from the photos which I can't sell elsewhere. It pays 5$ per sold photo. And you get paid that amount. As they are going to sell the photos for an amount around 10$ or so. It's hard to make money as the quality of images getting sold usually means the DSLR level photos get sold quickly than camera photos.
This is a social network where you may find people posting images and status like Facebook. And they get paid based on the likes. So you may have to find a large social group to join for making money here. Usually college group makes good money here. The payout is in 5$ increment like say, 5, 10 etc.
These are some of the apps that you can use to make money. Do note that it is extremely hard to make money with apps. And you have more luck by creating your own website and selling content to them.