Reusable condoms went into mass production thanks to Charles Goodyear's invention of vulcanized rubber. In the United States in the mid-1930s, disposable prophylactics were the rubber-of-choice and were produced at a rate of about 1.5 million a day. At the time, condoms were used solely for contraception.

When the pill put the responsibility of contraception on the shoulders of "liberated" women in the late '60s, it almost spelled the end for the condom. But with the rapid spread of HIV infections in the 1980s, the condom surged in popularity as a tool to prevent sexually transmitted diseases.

The first vibrator, developed in 1869, was steam-powered. Soon after that, the medical industry began constructing very large electrically powered contraptions for treating "female disorders." During the late 1800s, vibrators were not designed for home use. They were either too costly or too large, so some women resorted to smaller, hand-cranked models.

By the turn of the next century more than a dozen manufacturers had created less expensive battery or line-powered vibrators. Now the discriminating woman could afford one. Thanks to home electricity, the vibrator became the first electrical device invented after the toaster. It was at the height of medical quackery and these devices were touted as cure-alls.

Compared to penile prosthetic implants and penile injections, VCDs were the first noninvasive way to produce an erection, but they're not perfect. They can be very painful, requiring the user to wrap rubber bands to control blood flow after pumping, and the erection lasts only 30 minutes or so.

Research for the oral contraceptive pill began as early as 1901 when physiologist Ludwig Haberlandt discovered that hormones regulate menstruation. Almost two decades later Haberlandt demonstrated how to stop ovulation by transplanting the ovaries of pregnant rabbits into nonpregnant rabbits.

First registered in the United States in 1960, the pill's first few years on the market were extremely controversial. Originally, the pill was recommended only to married women to regulate menstrual disorders. As years passed, women started talking openly about sex and contraception. By 1968, public demand and the increase of doctors willing to distribute the pill as a contraceptive created a sexual revolution.

Penile prosthetics are supposed to make the penis rigid so sex is possible. They do not add length to the penis, nor do they give a man any more virility. Early attempts were made to create a permanent erection by implanting cartilage inside the penis, but the cartilage soon dissolved.

The first useful prostheses didn't appear until the 1970s. The most popular prosthetic was designed by Dr. William Scott. It's a silicon penile implant that inflates and deflates when the user squeezes a pump implanted in the scrotum.

Other noninflatable models don't let the penis go back to a flaccid state and may require owners to wear baggy pants to avoid ridicule.

Prosthetics are still popular today and doctors perform more than 25,000 penile implants a year.

Teledildonics, or cybersex, is geek-speak for having virtual sex through a computer. It may have started with fantasy videogames such as "Leisure Suit Larry Goes Looking for Love" and "Virtual Valerie." Cyberdildonics is another term for teledildonics; it was coined in 1991.

The most popular pornographic DVDs, such as "Virtual Sex With Tera Patrick," let the viewer simulate having first-person sex with a porn star. However, today's interactive-DVD technology is far from the Holy Grail of geek sex.

Ultimately, the goal of teledildonics is for two people to connect computer-controlled devices (including dildos, sheathes, and suits) to their bodies (specifically their genitalia) and sexually stimulate each other remotely. Vivid Entertainment has been working on a virtual sex suit for years, but given the nascent stages of tactile technologies it'll be a while before it hits the market. Until then, rent the movie "Strange Days" for a peek into the future of cyberdildonics.

Viagra has unleashed another sexual revolution by making impotence less of a stigma. Today, former presidential candidate Bob Dole, baseball star Rafael Palmiero, and publisher Hugh Hefner all endorse it. Prior to Viagra, one could barely get a man to mention impotence to his doctor, let alone talk about it on national TV.

Viagra works by relaxing portions of penile tissue to let blood flow through erectile chambers while simultaneously suppressing the chemical that causes the penis to go limp.

Viagra, generic name sildenafil, was originally developed as a high-blood-pressure medication. But doctors soon realized that hypertensive men taking sildenafil were experiencing a significant number of erections. Thus began the development and use of Viagra as a high-profile male sexual aid.

However, Viagra is about to face stiff competition from two clones, Cialis and Vardenafil, which improve upon the original sildenafil molecule and are soon to be approved by the Food and Drug Administration.

Cialis' benefits over Viagra is that it works faster, and it can be combined with food and alcohol. Its duration of effectiveness make it possible for a man to have sex multiple times from a single dose.

Viagra does not operate all by itself. The man who takes Viagra still needs some sort of sexual stimuli, either visual, audible, physical, to produce an erection. Apomorphine works on the part of the brain that stimulates sexual desire.

Unfortunately, Apomorphine is not more effective than a placebo and was significantly more toxic, with side effects that include nausea, dizziness, sweating, headache, and sleepiness. As a result, the FDA has rejected it.

Although unavailable in the United States, Apomorphine is still available in Europe under the brand name Uprima. Melanocyte-stimulating hormone (MSH) and pro-opio-melanocortin are Apomorphine alternatives. They're in the early stages of development (and years from FDA approval) and are designed to aid in male arousal.

Ovaries produce both female and male hormones. Female hormones are important for maintaining fertility and femininity. Recently, doctors discovered that women need male hormones known as androgens to maintain a healthy sexual drive.

When a womans production of these hormones subsides, sexual arousal problems arise. In preliminary studies, treatments with these male hormones have been able to restore a womans sexual desire. But how much of androgens a woman needs to be sexually active is still unclear.