For PC: iKKEGOL Upgraded USB Triple Foot Pedal Switch Control 3 Three Key Foot switch
This USB footswitch can be used with AutoHotKey (PC only) to control Ableton in some very handy ways. Personally I use it to start/stop playback, to undo or redo a loop recording, and to undo/redo session takes in Ableton. See the video below for examples of how it can be used to dynamically control your loop making process.
Note for Mac users: This foot switch will work on Mac. But, you have to have access to a PC in order to be able to assign keys to the foot switch. (That requires software which runs only on PC.) Once the keys are assigned, they are saved in the pedal and you can then plug it into your Mac. Then you use Automator on Mac OS instead of AutoHotKey. Instructions here…
For Mac : Kinesis Savant Elite2 Programmable Triple Foot Pedal (FP30AJ- with Extra 4th Jack)
While much more expensive than the PC foot pedal, this pedal does work with the Mac OS, including the ability to program macros into the pedal.
Behringer FCB1010 Midi Foot Controller
This MIDI foot controller is a more expensive (and more versatile) alternative for foot control. It can be used with Mac or PC and combined with Bome MIDI translator to perform the necessary functions.