need a sniffer for yahoo/msn voice chat :) ready to buy a commerical
one. I am using eBlaster for keystrokes.

Is this something like what you want?

http://freshmeat.net/projects/imsniff/

Theoretically, I would think any packet sniffer would work for your
purposes.  You just need to intercept the data being transmitted and
recompile it into some usable form.  I'd try using Ethereal.  I've
never tried sniffing voicechat traffic myself, but I am guessing that
it probably sends the sound as binary data so you'd need some way to
create a sound file out of the data you collect from the packets.

imsniff can only log the "typed" messages. I have not seen anything
which can decode voice traffic!

though i am a technical guy but i still think its not easy to write a
sniffer which can decode voice traffic. for text messages things are
easy. but for voice, yahoo/msn may be using propritory protocol for
decoding and compressing the data.