I’ve occasionally pondered whether there might be a benefit to getting some foot pedals / foot switches for my Kinesis keyboard. Since reading the Pragmatic Programmers’ TextMate book, however, I’ve realized that many of my editor’s handiest functions are meta key-based (that is, key combinations which involve Command, Option and Ctrl). And, while I’m entirely pleased with my Kinesis, its layout does make it slightly less convenient to hit some of the meta keys (as compared with a regular “rectangular” keyboard).
So, I decided to look into the feasibility of getting foot switches and came across this post on Ask MetaFilter which specifically asks about foot switches for Macs. Unfortunately, I learned that, while Kinesis offers USB-based foot switches, OS X has a limitation whereby input from one USB device can't modify the input from another USB device. Put another way, meta-keys can’t be assigned to Kinesis’ USB foot switches if you’re using a Mac (d'oh!)
After some additional searching, however, I found a couple posts about a fellow that used Kinesis foot switches on his Mac. (Wha?) Well, as it turns out, USB foot switches still don’t work on Macs (for meta keys), but Kinesis also offers a version of their foot switches which connect directly to a port on back of their keyboards (bypassing the OS entirely):
I have two Kinesis single-action foot switches. If you use a Mac, you have to buy one of the foot switches that plug directly into the Kinesis keyboard and not the USB foot switches. Apple won’t let one USB device modify the input of a separate USB keyboard or mouse. I have one foot switch acting as Ctrl and the other acting as Alt/Meta. I’ve heard different stories from different people — people tend to either love or hate foot switches. I find that they are really convenient when I'm doing “heads down” work in Emacs. They took a bit of getting used to initially, but when I use them, they offload an awful lot of the effort of working in Emacs to my feet. […]
I was pleased to learn that the meta key thing could work out after all. And, after mulling it over a bit, I’ve decided to give it a shot — I’ve ordered two of Kinesis’ single-action foot switches. Once they arrive, though, I’ll still have to decide which key to map to which foot. At the moment, I’m leaning toward assigning Ctrl to my left foot and Option to my right foot (since that would mirror the left-to-right arrangement of the default Mac keyboard).
Update 2007-05-03: I ended up assigning Option to my left foot and Ctrl to my right foot. — as Allan Odgaard mentioned in his screencast on Text Transformations (in HTML), “Ctrl-Shift are the modifiers we always use for Bundle items”. Since Bundles are the primary key-consuming resource in TextMate and, arguably, its most useful feature, I figured I’d bind the Bundle-related modifier (Ctrl) to the stronger of my two feet. (I’m right-handed, so I guess that makes me right-footed too?)