Type2phone - Type2Phone: Use your Mac as keyboard for iOS devices
AnySoftKeyboard - Android (f/w 1.5+) on-screen keyboard for multiple languages.
Typeeto - Use Mac’s keyboard to type on iPad, iPhone, Android, etc.
Hacker's Keyboard - Are you missing the key layout you're used to from your computer when using an Android device?
1keyboard - Type on your iPhone, iPad or AppleTV using your Mac keyboard
Gboard - Google-powered keyboard with search, GIFs, emojis and more!