I’ve merged my Marlin modifications with a newer version of Marlin, in a new github repo.

Status info GLCD screen for DOGM LCDs
display Z coordinates to hundreds, not just tenths
display SD print progress percentage numerically, not just with the bar.
display endstop state by toggling capitalization of X,Y,Z labels in the coordinate line
display 0% instead of — when fan is off.
display long filename when printing from SD instead of short 8.3 filename
Makers Tool Works LED controller
send events to the MTW LED controller introduced with the MendelMax 3 to display printer status. See bottom of Configuration.h
Fan control enhancements
Added a Fan Limit feature to constrain max fan speed using a panel menu item
Added Fan Ramping, to slowly spin up fan. Intended to avoid shocking PID to prevent temp drops when activating fan.
I added a custom ‘OhmEye’ menu at the top level
Purge Extruder does a short extrude
Select SD File to preselect a file on SD card without printing immediately
Print Selected file immediately begins printing preselected file
Move Z to 0 does exactly that
Preheat Bed does exactly that
Preheat PLA activates the current PLA profile
Preheat ABS activates the current ABS profile
Move Z allows manually moving Z axis in 1mm increments
Flow Rate sets the extrusion multiplier for extruder 0, default is 100%
Max Fan sets the maximum fan speed. Any command to spin the fan higher than this value will reduce to this value
Set XYZ to Zero makes the current physical position 0,0,0
Set Z=Z+10 increases the coordinates of Z by 10 for each press. This is handy if I want to move Z below zero for some reason.
Home Z Axis does exactly that, for Z only
Home XY Axis does exactly that, for XY only. Probably commented out because I usually have XY endstops disabled.
Zero SD Position moves the printing position in the currently selected file to the beginning
Motors/Fans Off turns off fans and disables steppers but does not change heaters
All Off turns off heaters, fans and steppers
Other stuff
I commented out the Contrast menu because it does nothing on any RRD style GLCD panel as far as I know
Autoretract was broken, I fixed it and submitted upstream to main repo