Following links from Stuart about running multiple Skype instances I came across the Skype Forums
where people are talking abut how to run multiple instances of Skype,
but also streaming Skype conversations into other VOIP and Net2Phone
services using a nifty gadget called a Virtual Audio Cable.
Virtual Audio Cable is a Windows multimedia
driver allowing you to transfer audio (wave) streams from one
application to another. It creates a pair of Wave In/Out devices
for each cable. Any application can send audio stream to Out
device, and any other application can receive this stream from In
device. All transfers are made digitally,
providing NO sound quality loss.


[...]


If more than one applications are sending audio to VAC,
it will mix all streams together. If more than one applications
are receiving audio from VAC, it will share the
same audio data between all targets.


[...]

VAC is useful to record application's audio
output in real time (for example - Generator, Reality
or other software synth), or transfer a sound stream to another
application processing it. You can, for example, use two or more
software audio generators/synthesizers/sequencors to produce
audio streams sending them to VAC Out, and
record the mixed stream from VAC In using any
recording software - Windows Sound Recorder, Sound
Forge, WaveLab, Cool Edit,
Gold Wave, Cakewalk, Cubase
etc.

This opens up all sorts of interesting possibilities like running a
stream from a Skype conference to an internet radio broadcast.
Very cool.
[Curiouser and curiouser!]