Virgin healers - Explore the magic of virginity (stereotypical "magic is lost when virginity is lost" dilemma)
Magic capabilities of fetuses and semen - Explored somewhat in my "Three paths of undeath" (or whatever) post. Idea: Gargoyle or impish demon formed by the fetus of a female made pregnant by a nether entity.
Rifts of energy caused by birth and death - Possible cause for ritual sacrifice is the rift caused when the soul departs. Similarly with births -> A birth is a great boon for "white" magic.
Bond of love - Magic capacity of love between two individuals. Exploring the theme somewhat in my "Prophecies of Love" campaign. Love strengthens magic between magic users, especially if they cast in conjunction.