Researching "cracked head" I came across a product called Heal-a-Seal:
http://www.heal-a-seal.com/WARPED-CRACKED-ENGINE-HEADS-CYLINDER-BLOCK-CRACKS-REPAIR.html]HEAL-A-SEAL BLOWN HEAD GASKET, WARPED/CRACKED ENGINE HEAD, CYLINDER LEAK REPAIR KIT
Could this actually work?