I've built a simple graphical tool that allows the user to explore the tonal space by playing any notes. You can see it in action here:
The interface is built using PyGtk. It sends MIDI events to whatever device you tell it to use and can set the instrument to whatever you want. It uses sysex events according to the MIDI tuning standard to do the tuning. In the demo, I'm using Timidity++ running in server mode to receive the MIDI events and produce the sound.