Max for Live devices are plugins for Ableton Live, built with Max.
Here are my devices made specifically for interacting with Elektron gear (primarily the Machinedrum and Monomachine).
All 4 devices on this page are free to download, but please don't redistribute them without permission.
Program Launcher
Program Launcher fires slots or scenes in the session grid based on MIDI program change messages, making it easy to build sets that follow pattern changes from hardware sequencers.

MD Alert
MD Alert sends sysex messages to a connected Elektron Machinedrum to display custom messages on it's screen.
Up to four messages can be bound to different MIDI note triggers, or the send buttons can be automated. Useful for performance cues and reminders during live sets.

MNMRT: Monomachine Retrig Controller
Designed to control the retrig time parameter on the Elektron Monomachine using MIDI notes. Converts incoming notes into their frequency in Hz and sends that value to a selected MIDI CC.
Probably only useful for the Monomachine, but who knows :)

E Scenes
Format your session view to reflect the Elektron workflow.
Creates up to 128 scenes if they don't already exist, and then renames them A01 through H16 to match Elektron's pattern numbering.
