Body modification isn't something i'd commit to, the thought i might later regret what ever work i got done makes the whole thing an entirely undesirable activity.
Things like piercings and tattoos are the most common body modifications in the west along with make up and hair dye being the most popular.
Plastic surgery once conceived was very popular amongst women but men have begun to show just as much interest of late.
In the documentary "Body Modification" by national geographic a man was not satisfied with the appearance of his posterior. He likened plastic surgery to car maintenance, "You would go out and re-service your car, you would change the oil to keep it up for maintenance, so why wouldn't you on your body."
One man got chest implants despite being in incredible shape and hired as a model. His operation caused quite a stir, he was totally unaware that chest implants for men is a taboo.
http://www.cracked.com/article_16853_the-8-most-horrifying-body-modifications.html
These are considered rather extreme in the western world but only because they aren't popular.
Plastic surgery is just as invasive and require you to be entirely anaesthetised which is arguably a much more extreme length to go for beauty and fulfilment.
In other cultures people wear neck rings which significantly distort the positioning of the shoulders, it's not been proven as to whether this is harmful but there are stories of women being short of breath and even becoming light headed once removed. I think this sort of body modification is best to steer clear from as it's not medically proven to be safe.
http://www.iamdann.com/2012/03/21/my-magnet-implant-body-modification
http://www.iamdann.com/2013/02/15/magnet-implants-can-actually-be-pretty-annoying
Magnet implants are more of a fun gimmicky body mod, it'll give you paper clip levitating powers, however engineers can make good use of them by easily being able to detect live wires. The magnetic field will make the magnet under their skin exert some force so they'll literally feel whether or not a wire is live or not.
At first magnet implants were not entirely safe and could corrode and leed to infection, newer technology has given the implants a much more robust outer shell so they don't easily corrode under the skin.
One problem with magnetic implants is that an MRI scan is out of the question without having it removed. Aswell as that it can cause discomfort if a powerful enough magnet is passed over it, the polarity might switch and leave you needing to massage the magnet back into the correct position.
The initial procedure is quite quick, only taking around 20 minutes however the healing stage takes much longer, it can be left swollen and numb during the several weeks of healing. The tissue must be seperated from the muscle so that the magnet can be inserted, this inevitably reduces the sensitivity of that part of the skin, nerves will have to be re-routed through the adjacent skin instead of directly down into the tissue.
The magnet loses it's potency over time and the effects will be reduced.
http://kpsurgery.tumblr.com/
In South Korea plastic surgery is a social norm for women, the discrimination they face in job and tertiary education applications demands that they get the surgery to progress in their career.
http://news.bbc.co.uk/1/hi/health/1147874.stm
This girl dreamt of becoming a flight attendant and ontop of that was worried that her height would be disadvantageous and maybe even prevent her from driving, so she had leg extension carried out to alleviate that anxiety and pressure. As a result she can now live her life not worrying about her height and she has a very real chance of being hired as a flight attendant. Had she not had the operation her dream career wouldn't be possible as anyone under 5 foot 3 is declined for safety reasons.
http://tattoo.about.com/od/piercingsgeneralinfo/a/Finding-A-Job-When-You-Have-Tattoos-Piercings-And-Or-Body-Modifications_2.htm
Body modification or body art can severely restrict where you can be potentially employed as it is still very much an undesirable trait. There are however a few companies who have expressed their body-art-friendly hiring policies.