How to share Mac audio over Skype with the microphone?
Turns out I had some strange Core Audio driver issue.  Every time Skype was running, process "coreaudiod" would fire up and begin to hog CPU like crazy.  I fixed permissions on my boot volume and it fixed a bunch of stuff related to iTunes, which apparently also fixed whatever was going on.

Once the coreaudiod issue was resolved, here's the setup that is working perfectly:


Skype "microphone" (input) set to Soundflower (2ch)
Aggregate Device created, consisting of Built-In Microphone and Soundflower (2 ch.)
Reason set to use the Aggregate Device
SoundflowerBed set to output to Balance.


Now all I have to do is create an audio track and enable monitoring, and I can hear myself in the mic, while normal Reason audio flows out both to Skype and my Balance to my headphones, and all is well with the world.