This is a work in progress! Feel free to add missing entries and to turn entries into links to the corresponding description in the GCodes wiki page.

M92 Set steps/mm

M208 Set axis limits and home positions

M569 Set motor direction

M584 assign drivers to axes and extruders

G29 Mesh bed compensation

G30 Set Z probe parameters

G32 True bed levelling; also 3-, 4- or 5-point bed compensation (deprecated)

M557 Define mesh probing grid

M552 Enable/disable networking and set Ethernet IP address

M575 Set serial port parameters

M587 Configure network protocols

M587 Add WiFi network or list networks

M588 Delete WiFi network

M589 Set own access point parameters

G32 Calibrate printer

M569 Set scaling factors

M574 Configure endstops

M119 Get Endstop Status

M4 Pause/Wait

M42 set pin state

M260 Send I2C bytes

M261 Send/receive I2C bytes

M280 Set servo state

M281 Configure trigger

M282 Check trigger

G10 Set tool temperatures, tool offsets and workplace coordinate offsets

M104 Set tool temperature

M105 Report temperatures (for Marlin/Pronterface/Octoprint compatibility)

M109 Set tool temperature, select tool if necessary, and wait until temperature reached

M116 Wait until temperature reached

G28 Home axes

G92 Set axis position and flag axis as homed

M208 Set axis limits and home positions

M929 Configure logging

M117 Display message

M300 Beep

M291 Display message, optionally wait for OK/Cancel

M292 Acknowledge message

M201 Set accelerations

M203 Set maximum speeds

M204 Set printing acceleration

M208 Set axis limits and endstop positions

M566 Set maximum instantaneous speed change

G0 Rapid/uncoordinated move

G1 Linear move

G2 Clockwise arc move

G2 Anticlockwise arc move

M23 Select file to print

M24 Start or resume print

M25 Pause print (asynchronous)

M27 Report SD print status (for Marlin/Pronterface/Octoprint compatibility)

M32 Select and print file

M37 Select and simulate file

M226 Pause print (synchronous)

M207 Set retraction parameters

M220 Set speed factor

M221 Set extrusion factor

M592 Configure nonlinear extrusion

M572 Set or report extruder pressure advance

M593 Configure Dynamic Acceleration Adjustment

M569 Set scaling factors

M911 Configure save-state-on-power-loss

M916 Resume print after power loss

M20 Mount SD card

M21 Unmount SD card

M30 Delete file

M36 Return file information

M38 Compute SH1 hash of file

M39 Report SD card parameters

M360 Set microstepping

M569 Configure driver timing, direction, chopper control, enable polarity

M584 Assign drivers to axes and extruders

M906 Set normal motor current

M913 Set percentage of normal motor current

M915 configure stall detection

M563 Create or delete tool

T Select tool