I just wanted to let you all know about some software that I have developed over the last 6 years in Max/MSP. Its called Kenaxis (http://www.kenaxis.com/)
and is a bit like Radial but with a more open angle.
I've used it to improvise live with folk like Fred Frith, Mark Dresser, Evan Parker, and Uri Caine. It allows for realtime sampling or playback of prerecorded loops. It also has a granular synth engine and lots of ways to set up process type situations that are great for creating surprises while improvising or ever shifting sonic creations for installations and the like.
I also have a multi-channel version call Kenaxis VBAP that allows for anywhere from 3-8 channel setups using Ville Pulkki excellent VBAP object.
Other than the VBAP object - this was created using only Max/MSP standard objects. If anyone has any questions about the software or how I managed to do a particular bit of programming I am happy to answer any questions.