it depends how "outside of the box" you are willing ot do
you can hack a Miduino into any old set of organ bass pedals, these are quite easy and cheap to come across..cos they dont need to work (as lond as the switches work) you just rip them out and get soldering...
http://tomscarff.110mb.com/bass_pedals_ ... no_USB.htm
the other option is the FCB1010
these are easy to get hold of and if you do as i did on mine, is ready to use quickly
basically the pedals are in two rows of five so you need to think of the best system for you to rememeber whats what i do the following
D F A C# F#
C E G B D#
obviously this is a differant system to a normal keyboard, and it misses out some note, but for the keys i play in this gets me by.
another option would be to limit each patch bank to a specific key so you could go
Bank 1
D F A C E
C E G B D = C maj / Am
Bank2
A C E G B
G B D F# A = G maj / Em
this is a fun modal way of playing cos you can improvise with your feet really easy to create wandering patterns...
also you could set one of the pedals up to pictch bend (if the unit you use it with supports it )
you could then use that to band up +12 and grab another octace and a half .
let me know how you get on cos i love stuff like this
I currantly create whole live orchrstras through a guitar feeding GR-30 with an arp, then sending miti notes across to a synced microkorg and proteus , each with their own transposed strings patch and arps... lush and very very dense but also completely reactive to my limited playing skils
