Gboard - Google-powered keyboard with search, GIFs, emojis and more!
Emoji Keyboard - Allows searching and inserting into other applications near thousand emojis.
Typing Speed Test - A simple typing test to see how fast you can type
Swiftkey - SwiftKey keyboard allows for seamless typing and adapts to the way you type, so you can spend less time correcting typos and more time saying what you mean.
keyboardlayouteditor - Powerful, visual designer for designing and editing keyboard layouts.
AnySoftKeyboard - Android (f/w 1.5+) on-screen keyboard for multiple languages.