I have heard (but am very skeptical of):

- different sex positions favour conception of boy/girl (wasn't sure if is too rude to mention specifics here!)

- Carrying the baby high means its a girl; low a boy.

- craving sweet foods means your having a girl; salty/savoury cravings mean a boy

- having an unused pram waiting in the house before baby is born brings bad luck

- babies are born to reincarnate an elderly person in the extended family who most recently passed on