Tongue--Tongue piercings are also good for play during kissing, and also great for oral. There are vibrating tongue rings that can be bought for the purpose of oral.
Nipple--Nipple piercings are bars going through the nipple. When touched, they can send waves of pleasure through the body. Much like how when a person is turned on, their nipples are extra sensitive, the piercing can add to that sensitivity.
Prince Albert--This is the most popular penis piercing, and can be very stimulating. It is a ring or a barbell in the opening (urethra) of the penis.
Guiche--The base of the scrotum is pierced through the perineum (the circular mound between the testicles and the anus).
Clitoral Hood--Horizontal or Vertical piercing over the cover of the clitoris. Rubs against the clit for maximum sexual pleasure.
Inner Labia--Piercing of the inner lips.
Outer Labia--Piercing of the outer lips. Tends to be rejected more than the inner lips.
Overall, piercings can spice up your sex life, but make sure to take proper care so as to not get an infected piercing. Research a piercing before you get it, and make sure you are willing to handle the healing times. If it all checks out--go for it!!!
About.com--Female Genital Piercing Guide.--follow the links to each piercing information.
BMEzine Wiki--Triangle Piercing.