DEZ 2019:
Someone compiled this beautiful website:
https://minimidi.world
So I think I'll probably stop adding to the list below.
[EDIT November 2019: I am very sorry, I confused type A and type B, now corrected]
Type B; Polarity Arturia: Ring: Data; Tipp Vcc
Type A; Polarity Korg: Tip: Data; Ring Vcc (NOW THE MIDI 2.0 STANDARD!)
Polarity non-TRS (a.k.a. MFB): Sleeve & Tip
ALM Pamela's New Workout with Expander (Output; polarity internally swap-able)
MFB Nanozwerg Pro (Input; Polarity NON-TRS!!)
MFB SER-1 Pro (Output; Polarity probably NON-TRS too)
LPZW.modules WK3 (Input/Thru; Polarity auto/switchable)
LPZW.modules SCHLEUßIG (Input; Polarity auto)
LPZW.modules TRAM8(Input; Polarity auto)
Erica Synths Drum Sequencer (Input; unknown)
Five12 Vector (I/O; Arturia)
SDS Digital WifiMidi (Output; Korg-ish)
SDS SDS_VCO (Input behind panel; User configurable))
SDS Reflex LiveLoop (Input behind panel; user switchable)
SSF Bantam (Input; unknown)
Soulsby AT-Arp (Input; unknown)
Malekko SYNC (I/O/Thru; Arturia)
1010 Music MX4 (Input/Thru; polarity Arturia)
1010 Music fxbox/bitbox (Input; polarity Arturia)
1010 Music Toolbox (I/O; polarity Arturia)
1010 Music MOK Waverazor (In; polarity Arturia)
ADDAC System ADDAC221 (I/O; Polarity Korg)
ADDAC System ADDAC222 (I/O; Polarity Korg)
Pittsburgh Modular Liveforms SV-1 (Input; Arturia)
Entrospec iungo (I/O; Polarity Korg - 2.5mm jacks!!! why, oh why? )
Flame Quad-CV-Recorder (Input; Arturia)
Flame 4Vox new version (Input; Arturia)
Flame Filterbank (Input; Arturia)
Twisted Electrons Crazy8 Beats (i/o unknown) - also standalone
Pittsburgh Modular Lifeforms Voltage Lab(Input; ?)
Pittsburgh Modular Sequence Designer 128 (I/O; Arturia)
Zetaohm FLXS1 (I/O; Korg)
VPME.de trig31 (Out Arturia)
Dreadbox Lil' Erebus (In, Korg?)
Analog Solutions Treadstone Eurorack (In, unknown)
mxmxmx C2M (In/Out user configurable)
Michigan Synthworks MBrane (MI YARNS) (I/O unknown)
Shakmat Modular Clock O' Pawn (In: unkown)
Futureretro MIDI BUS expander for Trax! (I/O Arturia)
Supercritical Synthesizers Demon Core Expander (i/o auto-crossover in & user selectable out)
Westlicht Per|former (i/o polarity Korg)
XOXO MIDIXO (Model 92½) (i/o polarity configurable)
Polyend Poly 2 (i/o polarity Arturia)
Dreadbox Cases (Input ...)
Intellijel Palette 4.5U Cases (i/o polarity ?)
Non Modular:
- Make Noise 0-Coast (In; Polarity Korg)
- Korg Electribe 2/Sampler (I/O; Polarity Korg)
- Korg SQ-1 (Ou; Polarity Korg)
- Arturia Beatstep (Out) & BS Pro (I/O; Polarity Arturia)
- Novation Launchpad Pro (I/O; Polarity Arturia?)
- Novation Circuit (I/O; Polarity Arturia?)
- Novation Circuit Mono Station (I/O & Thru; Polarity Arturia?)
- Faderfox SC4 (I/O; Arturia?)
- Twisted Electrons Acid8 (I/O unknown)
- Twisted Electrons AY3 (Input unknown)
- Twisted Electrons Crazy8 (I/O unknown)
- Twisted Electrons hapiNes(In: unknown)
- Twisted Electrons TherapSid MkII(I/O: unknown)
- IK Multimedia Controllers, Midi Interfaces, UNO Drum&Synth (probably Korg/Type A)
- Analog Solutions Treadstone(In, unknown)
- Teenage Engineering OP-Z with oplab (I/O; polarity Korg??)
- Teenage Engineering Pocket Modular 16 (Output: polarity Korg)
- Elektron Model:Samples (I/O polarity ?)
- Critter And Guitari Organelle mk2 (I/O polarity Arturia)
- Empress Effects Zoia (I/O polarity ?)
- M-Audio Air Interface Series (I/O Type ?)
DIN-TRS Mapping according to MIDI.org

A fun DIY project for the cold winter evenings to do with the whole family:
https://www.midi.org/articles-old/updat ... din-cables