When I used to play keyboards in a band I always worried about setting up all the patches for a song, on each of the synths, and often spent ages mapping complex split and layering effects so I could control as many sounds as possible from a single keyboard.
At the time I started designing a piece of hardware that would route all my midi signals, and automatically configure the system for each song. I actually started building it, but it never got completed...
A few years on, and everything is in software, so here's a software (AU Host) version of what i imagined back then. Select up to four Audio Unit synths, and map them over the keyboard. You can save those as "songs", or arrange a whole bunch of songs into a "setlist". At the gig just fire it up, and step through the songs via midi patch change!
it's in a pretty basic state right now, but it is functional, so I'm releasing it to try and get some feedback - to see if there's any interest in actually using it!
The main limitations right now are:
The other missing features will get added as soon as someone persuedes me to do it. A word of warning though - adding those features may break file compatability, so don't expect to be able to load v0.1 files into V1.0.
V0.2 now allows you to re-arrange setlists.