Zyklus Improvisor is a software 8-track midi looper made with Max/Msp 5. Record and loop short sequences on the fly or use the step recording facility. With the build-in harmonizer you can change your sequences to another key and scale just by pressing a chord on your keyboard.
Zyklus Improvisor also has 8 step-arpeggiators on board. You can lock your key input for each arpeggiator and still keep things harmonized.
A sound name database is provided for easy access of all your synths because you can program your own midi BankSelect and ProgramChange messages too.