What discontinued feature do you miss from phones or other technologies?
For me its the 'Knock Code' that LG had on their phones (I really wish LG still made at least the V series phones)
Basically there was a four-square area and you set up a sequence of where you would tap to unlock the phone. That set of squares was only shown when you set up the code
Then, to unlock your phone, you would tap those areas in the sequence you set up (even with the screen off).
Fingerprint readers are nice, but I really do miss the knock code
Edit: did find this article with a way to do the knock code, but if done wrong, could brick your phone I guess.
Plus, article is from 2014. When I looked at XDA's info on it (they also being the developers) it looks like development on it is over, but individual modules may or may not still be supported by their devs
SensMe in Sony and Sony-Ericsson phones and players. It was the tool that analyzed your music collection and sorted it according to energy, mood and tempo.
The best variant was on the later products whey you had a list of channels representing either moods/styles (Energetic, Emotional, Lounge, Dance etc.) or time of the day (from 'Morning' to 'Midnight'). The results were very good, especially for the time channels (except the morning) which were perfectly fitting the mood and pace of times of the day, much like Indian ragas. It really felt like your personal radio stations, freeing you from having to make playlists by yourself ever again...
It was discontinued in 2010s because of declared low adoption by users according to some obscure internal studies :( I've been dreaming of replicating it using Python ever since, but never had time to do a proper research.
Spotify?