There's a very nice tool named AntiMafia, created by a 'subvARTising'
group and based on a sound democratic principle. It can use peer-to-peer
protocol (Gnutella, I think) to syncronize some net-boycotting actions like
-Denial of Service- or more. I tried it, but it probably isn't fully operational
yet... It seems that the group did not develop some pieces of code...
I don't know, I'm not a programmer, but it is an Open Source Code for Windows
and I think someone able to programme could look into this useful tool.
epidemic.ws/antimafia/index.php