1. Hydrogen peroxide jetpack
This is the James Bond jetpack, powered by hydrogen peroxide and just barely light enough to wear on your back. Based on the Bell Aerosystems jetpack built for the U.S. military and first flown untethered in 1961, its propulsion is more like a water balloon than a jet engine. When the fuel comes in contact with a catalyst such as silver or platinum, the liquid quickly decomposes into water vapor and oxygen, expanding through two nozzles, and providing enough thrust to lift a 180-pound person.

State of the art: There are two major players. Tecaeromex offers the only jetpack for sale right now, and once you've laid down the $125,000 for the unit itself, you'll have to go through 50 test flights just learn how to control it. Then there's Jetpack international (Jet P.I.), the company that handles most of the exhibition flying these days. It flies the Go-Fast Jetpack H2O2-Z you see in the video above. It holds eight gallons of fuel that can propel it for 43 seconds at a maximum speed of 77 mph.

Limitations: Even though both jetpacks use the latest aerospace materials such as carbon fiber, Kevlar, titanium and aluminum, the 78-pound H2O2-Z, the longest-flying model yet, is still limited to a maximum airborne time of 41 seconds. The jetpacks' peroxide propellant is expensive and hard to come by, they're so dangerous that only skydivers need apply, and they're difficult to learn how to fly since there's no simulator.

Applications: According to Tecaeromex's Juan Lozano, don't expect to depend on it to fly you to work every morning. For flying short exhibition flights, that huge chunk of change might be a good investment, says Lozano: "The flight time is very limited, but it is a great business for shows, special events and sport events because you charge about $25,000 for each flight. So the business is great."

Our take:To see a guy flying around with a jetpack is a spectacular sight, and that's the only use for the devices these days. It takes a lot of skill to fly one, too. If control of a jetpack could be computer-assisted, it would be a lot safer. This might be possible someday, according to Tecaeromex's Juan Lozano: "Now we see micro toys that are stabilized in flight. Maybe someday you will be able to fly your own jetpack with software similar to that used in the two-wheel standup vehicles like the Segway, that is computer stabilized." However, it's going to be difficult to extend the flying time of this design, because the weight of the fuel will become too cumbersome for most people to carry on their backs. This technology it looks like it'll be stuck in the realm of the carnival trick.

2. Martin Jetpack
More a personal helicopter than a jetpack, the FAA calls the Martin Jetpack an ultralight airplane. Its two ducted fans are powered by gasoline, and the $100,000 gizmo can theoretically fly up to 8,000 feet for 30 minutes on a full fuel tank.

State of the art: Because of the device probably won't be able to stay in the air with only one of its engines working, it's equipped with a parachute. Its automation can be set to limit its height, speed, and to avoid obstacles.

Limitations: It's so unwieldy it can hardly be called a backpack, it's impossible to walk around with it. Not available for sale yet, the company plans to deliver its first 10 jetpacks to customers in 2010. While it's been tested on a tether indoors, it still hasn't performed an untethered, unassisted outdoor flight.

Applications: Intended as a recreational vehicle, it also might be available for rental, similar to skydiving. It can also be used for surveying, rescue operations, and law enforcement.

Our take: This is more of a small plane that you strap yourself into than a jetpack, but it looks like it would give you a similar thrill to the one you get from a powered ultralight aircraft. Just steer clear of any birds.

3. JetLev-Flyer Water Jetpack
Strap yourself onto a pair of intricately controllable fire hoses, and you have yourself a JetLev-Flyer. Soaring over the water, its 33-foot hose is connected to a 255hp engine, pumping gallons and gallons of water through its hose and spewing it out its nozzles, letting you fly around at speeds faster than 40 mph for over an hour at full throttle.

State of the art: The company will be offering two different models, one is 155hp (selling for $170,614) and the other is 255hp (costing $191,384)). So far, the device hasn't made it beyond a few videos and demo flights.

Limitations: Because you're tethered to a vessel floating on the water below, you're limited by the length of the hose, which is 33 feet for safety reasons. That's about the maximum height you can fall into the water without danger of serious injury.

Applications: Created for pure enjoyment, this is more of a water sport akin to waterskiing than a transportation device. You're dragging a revving engine on a floating platform behind you, and your attached by a hose, so you'll need to be in a large lake where you can't hurt anyone.

Our take: This looks like it would be a tremendous amount of fun, and hovering above the water less than 30 feet below would add confidence and make it a lot safer. The backpack is also a lot lighter and less noisy than other jetpacks, because the power unit is 30 feet away at the other end of a hose.

BONUS: Turbojet pack T-73
Jetpack International's dream of a long-flying rocket belt could come into fruition with the T-73, a Jet-A-fueled jetpack with a turbine engine on board. The advantage? It could fly for nine minutes rather than the mere 43 seconds of its hydrogen peroxide brethren, at speeds up to 83 mph, traveling 11 miles. By the way, that pic you see above is not the T-73, but an earlier jetpack, because the T-73 doesn't exist yet.

State of the art: Jetpack International promised the T-73 unit two years ago, and it's still said to be on the way. They're not talking about pricing yet.

Limitations: That jet turbine engine spinning around at high rpm gets awfully hot. There is little information about this next-generation jetpack, with the company telling us that the T-73 "will be sold to qualified individuals that have undergone extensive training. Details to Follow." They added that "the T-73 is not yet for sale," and promised to contact us once it becomes available.

Applications: When the U.S. military experimented with a similar jetpack, it was deemed impractical. However, its mini turbine engine ended up powering cruise missiles. This technology could have significant military benefits, if it isn't in use secretly already. Its 11-mile range and nine-minute flying time could make it useful in all sorts of search and rescue operations, in addition to its spectacular recreational potential.

Our take: The ultimate goal of jetpack technology, it's still a daunting prospect to think that you're wearing a jet engine on your back, along with 5 gallons of kerosene jet fuel. Sure, you can fly for nine minutes without worrying about running out of fuel, but the sheer danger of the T-73's flying height, speed and flammability might be a buzzkill.

1. CD ripping of music to hard disk
   
2. Music and data streaming from your phone
   
3. Voice navigation

Hard Driving

The THX 5.1-channel surround system has 50GB onboard for music storage. Just slip a CD in, hit Record, and it starts ripping as many tracks as you want (the format is proprietary, bit rate unknown). Theoretically, after a few weeks, every road-trip album you want will be onboard, and you'll never hunt for a CD in the glove box again. As a bonus, the system sounds great (this is THX, after all). Listening to some Johnny Cash on CD, the speakers really conveyed his gravelly voice and every pluck of his guitar. DTS Natural Sound made everything — including highly compressed satellite radio audio — sound crisp and immersive (more detail on the THX system in the gallery below).

Just be sure you'll be on the road for a while if you want to rip a whole CD, though — when you shut off the car, the recording stops. That hard disk should really have more capacity, too; since portability isn't an issue, why not have 500GB? Or 500TB, for that matter?

Stream Time

Ripping is great, but as I said at the beginning, lugging CDs with you in the car is so '90s. If you want to skip that entirely, just pair your phone via Bluetooth and stream your music. Yeah, you get that extra hit of audio compression that goes with Bluetooth, but I didn't notice on most tracks. You can also transfer your address book and make hands-free calls easily, speaking through your car's sound system. Very cool.

Talk It Out

Lastly, voice navigation makes good use of the audio system by letting you verbally tell the GPS where you want to go. Like all voice-recognition technologies, this one's a bit tricky, often mishearing what you wanted. Once you get used to its quirks, though, you'll prefer it to tediously typing in addresses, and turn-by-turn directions come in loud and clear through the speakers.

There's room for improvement — mainly in the area of network data, which is provided solely by Sirius Travel Link. This supposedly kept the navigator informed of traffic disruptions, but if so, why didn't Sunday's huge gathering of emergency vehicles on the FDR register? Looking at Google Navigation on the Droid phone I brought with me at least showed a big red streak (indicating poor traffic), but the Lincoln system simply said there were no traffic disruptions, which was plainly false.

Even with that issue, though, the MKS still provided the best navigation experience I've ever had behind the wheel. And did I mention the EcoBoost engine, which, according to Lincoln, has turbo chargers that give the engine the power of a V8 while still retaining the fuel economy of a V6? Nice to have when you need to do fast lane-changing in New York traffic. While the $53,105 price tag is certainly a tad high, in this case you get a hell of a return on that investment.