Motorola Flipout
#Motorola

Secondary display on hardware keyboard
#LG

Physical keyboard on back of the phone that can be opened
#Motorola

Custom screen-off gestures
#Bluboo

Draw to search emoji
#Google

Linux on Dex
This allowed you to run linux applications inside desktop mode.
#Samsung

Two fingerprint sensors
#Huawei

Xenon flash
It was available in Samsung S4 Zoom and K Zoom and it was in testing phase of Xperia Z1 prototype
#Samsung

Gesture to Rotate Screen
#Smartisan

Swipe to Clear Icon Badges
#Smartisan

Fullscreen album cover on lock screen
#Google

Samsung Pay MST
#Samsung

Wikitude
This app allowed you to see places from your camera app.
#Sony

Baby crying detector
Once it detects baby crying it will automatically alert you on Galaxy Gear smart watch
#Samsung

Voice Recorder meeting mode
distinguishes sounds coming from up to 8 directions when recording, and indicates which sound comes from which direction when the recorded file is played back.
In particular, when you wish to, you can play back only the voices coming from certain directions by selecting them.
#Samsung