KeyApp.Top team offers app promotional services to Android developers. They can promote your app by keyword installs and standard installs for your application. Their installs can be geotargeted in USA, UK, Germany, India, Canada, Australia and they always expand new regions.
They have a huge number of users all around the world, so they pay them for each install, it’s incentivized traffic. In addition, they have discounts and bonus programs. You can get free trial (20$) to test their service after you signed up on their site and contacting them: firstname.lastname@example.org