http://cm.bell-labs.com/cm/cs/what/smlnj/index.html
Moscow ML is a light-weight implementation of Standard ML (SML), a strict functional language widely used in teaching and research. Version 2.00 implements the full SML language, including SML Modules, and much of the SML Basis Library.
http://www.dina.kvl.dk/~sestoft/mosml.html
Poly/ML is a full implementation of Standard ML available as open-source.
wikipedia.org dumped 2003-03-17 with terodump