I have just two things to say:
Princess Tutu
http://www.animenewsnetwork.com/ency...me.php?id=1267
Dennou Coil
http://www.animenewsnetwork.com/ency...me.php?id=6278
go, now! (princess tutu gets a little dark though.. actually so does dennou coil.. but theres nothing explicitly adult about them and theyre AWESOME)