JEuclid

JEuclid is an excellent MathML renderer, well written by Max Berger, a very knowledgeable person. Best of all, as a FOP (http://xmlgraphics.apache.org/fop/) plug-in, JEuclid allows to convert complex XML documents embedding MathML equations to good looking PDF. I highly recommend using JEuclid in your projects. I do that for mine.