Originally Posted by Spectacle
With ReWire, for example? So, Logic could be pulling down 3GB of RAM, and if you had more, that could be used by Reason through ReWire and, say, Amplitube 2 in standalone mode, as well as whatever is needed by your system?
I'm not sure about ReWire.. but you can route midi between the programs with the IAC, and can route audio between the programs with Soundflower.
The Dec 06/Jan 07 edition of Virtual Instruments Magazine has an article dedicated to this and goes through it step by step. They were able to load 7 gigs of samples on a Mac with 8 gigs of ram.