I used a jog/shuttle controller years ago doing video editing and this is a great idea for time line audio editing in Audacity.
I purchased a popular and reasonably priced edit controller the Shuttle Express.
http://retail.contourdesign.com/?/products/22
It works with linux (linux kernel has correct USB drivers for it) but if the application has no direct support for it you have to try to make a kind of "hack" implementation work for key bindings. Less than ideal for sure.
Being able to use such a controller with Audacity should would make my work easier.