Here’s a really cool little program I found on VesionTracker: MIDI Patchbay It does just what the name implies. This allows you to quickly re-route midi data without having to plug and unplug physical wires. It also opens up some new possibilities (combining to synths to mix their sounds, or harmonizing one synth). Personally, I think this program should just be built into OS X.
It’s pretty cool, and I can finally play my synths while in OSX.