http://xml.apache.org/fop/
Java-based
Developed by Apache Project
Current version outputs to PDF, MIF, text and PCL.
Examples:
Fop -fo inputfile -pdf outputfile
Fop -fo manual.fo -pdf manual.pdf
Can be used in conjunction with Xalan to directly process files:
Fop -xsl mystyles.xsl -xml manual.xml -pdf manual.pdf