Fuzzy classification programs?

I'm a newbie at fuzzy set classification, and I was hoping for some
suggestions for fairly easy-to-use/learn programs for doing basic fuzzy set
classification tasks (e.g. membership function creation, determination of
rule weighting, etc..)  Any suggestions?  How are the MATLAB and Mathematica
addons?  I have access to UNIX, PC and Macs, so platform isn't a problem...

Thanks!

--j