Literate Programming

http://www.cnx.org/

http://www.artcompsci.org/

http://www.wolfram.com/

http://fit.c2.com/

http://www.fitnesse.org/

http://www.matheclipse.org/

http://openrules.com/examples.htm

http://labs.jboss.com/portal/jbossrules

http://fit-for-rules.sourceforge.net/

noweb

http://literateprograms.org/

IBM XJ

IBM XJ http://www.research.ibm.com/xj/ extends Java with XML Schema so that the XML Schema types are first class Java types.