unzip, bkhive2, samdump2 and pwdump6 are released under GPL v2

unzip
http://infozip.sourceforge.net/UnZip.html

bkhive2
http://sourceforge.net/projects/ophcrack

samdump2
http://www.studenti.unina.it/~ncuomo/syskey/

pwdump6
http://www.foofus.net/fizzgig/pwdump/

A copy of the source code can also be obtained on ophcrack homepage:
http://ophcrack.sourceforge.net