Tooth Filing
Tooth filing is the reshaping of the teeth through the removal of a part of the tooth. This is not the same as "vampire teeth," which are generally caps added to the teeth.
If you go to a dentist, risks are minimal and will be explained to you in full. If you do it yourself, you risk permanent damage to the teeth. It hurts slightly less than getting a tooth drilled—anesthetic is often not required.
Strangely enough, tooth filing can reduce your chances of cavities and similar dental complications. This is thought to be one of the reasons that tribal cultures performed the procedure.

Earlobe Stretching
Most people can stretch to at least 2ga (1/4″) and still have the tissue return to normal when they remove the jewelry, but there really are no guarantees. Dont stretch your ears unless you are certain youll be okay with it forever. Once the elastic limit of the skin has been passed, or a large amount of additional tissue has been built up, the hole will not close again completely. A person who is either obsessed with stretching their piercings, or with showing off their many stretched piercings, is known as a Gauge Queen. Some wear this term with pride, others use it derisively.

Pierced Glasses
James Sooy and Oliver Gibson have come up with Pierced Glasses - the most minimalist eyewear since the Pince-nez was invented in the 1840's.

Tightlacing
Also called corset training and waist training, this is the practice of wearing a tightly-laced corset to achieve extreme modifications to the figure and posture and experience the sensations of a very tight corset. Those who practice tightlacing are called tightlacers. Some tightlacers call the corsets they wear training corsets.

Neck Stretching
"Neck stretching" is a bit of a misnomer because it is not in fact possible to stretch ones neck -- you can however force the ribs and collar down with enough time and dedication, giving the illusion of a longer neck. This is limited almost exclusively to traditional cultures, but in the West, some people also enjoy minor neck stretching, corsetry, and bondage for both aesthetic and ritualistic reasons.

-Extraocular Implants
The implantation of jewelry in the outer layer of the eye, this is one I must admit I had not heard of. Apparently first done in the Netherlands, it has come to the US. According to Dr. Christopher Rapuano, a corneal surgeon at Philadelphias Wills Eye Hospital, You can think of it as crazy. I mean this is invasive surgery where you are cutting the surface layer of the eye open to put a little piece of jewelry in. The first time I read about this I said, Oh, my God, who is doing this? The safety of this procedure will have to prove itself over time, since it hasnt been performed on many people, but the possibility for infection and complications is definitely there.