The Bodybugg is like having a personal trainer strapped to your triceps. The 2.9-ounce gadget uses four sensors to calculate your energy expenditure with 92 percent accuracy&8212;on par with in-the-lab measurements. An accelerometer tracks your movement; two thermometers gauge body
temperature (one's for your core, the other for skin); and a
galvanic-skin-response sensor measures sweat. Upload the data to bodybugg.com, and the site will chart your daily calorie burn against your intake. $500

Sit down, stand up, climb stairs&8212;Ossur's Power Knee is the first motorized prosthesis to give leg amputees fluid motion by simulating the movement of the real knee next to it. A series of sensors strapped to the healthy leg measure pressure and motion 1,350 times a second to determine where the leg is going and how fast. The data transmit wirelessly to an artificial-intelligence processor on the 10-pound, battery-operated Power Knee. The microchip controls a brushless motor that drives the device precisely in sync with its healthy neighbor.

For obese people, gastric-bypass surgery is a risky gamble to shed major pounds. Now a safer alternative is on the way: the gastric stimulator. In a reversible procedure, doctors implant Medtronic's matchbook-size Transcend II stimulator just under the skin in the abdomen. Once in place, the device sends a painless electrical pulse into the stomach wall about every six seconds. The electricity relaxes and distends the stomach, conveying signals to the brain that trigger feelings of satiety.

If there's a kryptonite for acne, it's heat. So scientists at Tyrell, Inc., invented the Zeno, a handheld rechargeable device that gives your pimples heat stroke. Hold the tip of the cellphone-size device to your zit for two and a half minutes, and a 16-bit microprocessor emits mea-sured pulses of 119�F heat. (It feels sort of like a hot compress.) Under your skin, bacteria produce stress proteins and self-destruct, halting the inflammation that creates visible blemishes and healing the area faster than other over-the-counter remedies&8212;typically within 24 hours.
$225;

Welcome to the future of prosthetic limbs: true mind control. For the first time ever, an amputee need only think about a movement-picking up a glass, for instance-and the 12-pound Neuro-Controlled Bionic Arm dutifully coordinates the task. Electrodes intercept the limb's residual nerve firings and feed them to a computer embedded in the forearm, which then commands six motors to move the device's shoulder, elbow and hand in unison. Thanks to hand sensors, the wearer can even gauge pressure and fine-tune his grip.
For now, the prototype arm fits just one man, Jesse Sullivan.

Daily insulin injections make it hard
for many diabetics to control blood sugar well enough to prevent serious complications like blindness and kidney failure. Now Pfizer and Sanofi-Aventis offer up the painless Exubera, an inhaler that delivers aerosolized insulin to the lungs, which quickly absorb the drug over their large surface area. A single puff just before meals can stabilize blood sugar as effectively as a shot. A Food and Drug Administration panel voted to approve Exubera this fall based on results from more than 52 clinical trials conducted over 10 years.

Needles hurt. Worse, they can spread disease. PowderMed's new vaccine gun, the PMED, requires no sharps. The flashlight-shaped device relies
on pressurized helium to shoot microscopic DNA vaccine particles just below the skin's surface at 1,500 miles an hour. The shot is painless because it hits just above nerve endings, where immunity-producing cells gather in large numbers. As a result, the PMED requires one thousandth the dose of a needle injection&8212;a major cost savings. And the powders don't need a fridge, so they're easier to store and transport.

For the millions of people with intractable pain, Prialt offers 1,000 times the analgesic power of opiates but without the addiction and waning potency. The secret is a synthetic compound modeled after a paralyzing toxin made by a Philippine cone snail. Whereas opiates boost
pleasure chemicals, a catheter implanted in the spine delivers Prialt directly to nerve cells to block the transmission of pain signals to the brain.