Fuse - Fuse is a UX tool suite for mobile app designers and developers.
Amazon Appstore - The Amazon Appstore is a place to purchase and download apps for your Android device.
Dropsource - Mobile development platform for building native iOS & Android apps
GetJar - Discover and play paid apps and games for free.
Siberian CMS - Siberian is an Open-Source and Free App Maker. Unlimited Push Notifications. Unlimited features. Fully Customizable. Download it and build your own app now!
F-Droid - F-Droid is an interesting alternative for Android users who want to try something different and not have to use the Goole Play store all the time.