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 the button assignments must be made on a PC first. Also, you’ll have to use Automator in Mac OS instead of AutoHotKey. For a pure Mac solution, see the next pedal below.
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.