for my 2p i do have an IUD and i love it. it is the mirena which is actually recommended for a heavy cycler, and since i have been on it between it and medications i take i don't really have a period. i know that might not be good for some younger women, but i have no intentions of having any more children, so i don't care about my possible fertility. the one experience i had with PP was in high school when i tried to use them. they swore they would not tell my parents i had been there, but then they called. i was really upset about that. i've had some terrible experiences with other doctors, like the one one lectured me on sex before marriage. i wrote to that doctor's supervisors. i was furious--what business is it of his who i have sex with? at the time i was in a monogamous relationship, but other than to tell me to be careful of stds etc he had no right.
It is a device, made of a coil of plastic, which is inserted into the uterus. Some are coated with copper or hormones, to make them more effective. They prevent implantation, by having the lining of the uterus changed by their presence, and also the hormonal ones can prevent ovulation. They are not for everybody, as some womyn get heavy periods from them, and you have to be careful not to get any STDs, as they can increase your risk of Pelvic Inflamitory Disease.
Some womyn do fine with it. I have endometriosis, so it is out for me. But, some do OK. Your GYNE history has to be reviewed by a good doctor or midwife before they insert one into you. It was the original "don't have to think about it" form of birth control. Womyn in Ancient Egypt used to use small pebbles as IUDs, more than 4,000 years ago.
Norplant works similarly to Depo Provera. The look of this thing did creep some people out. There were also problems with the things bursting, and with bad scarring, AND some insurance companies would pay to have them inserted, and then NOT pay to have them removed if womyn had side effects.