Unless your power supply is DC (i.e. you will only be plugging into an airplane, auto, or marine DC socket), there is no escaping the brick, which contains a transformer for reducing voltage and converting current from the wall into something the laptop can use. As it operates based on its physical properties (e.g. size of core, number of coils), reducing its size isn't a simple matter when the brick will be moved around (and bumped, dropped, or kicked) frequently, used in homes and businesses (and so must be shielded against electromagnetic interference), and fed inconsistent or "dirty" power from the mains, and must still be cheap enough to bundle with a consumer device. That is why even as laptops have gotten increasingly lighter and more powerful, the standard brick seems barely to have budged in size.

Therefore, you will need to look at third-party, aftermarket "compact" power supplies. Even these will not obviate the need for a brick, but US$100 should buy you a centimeter or two off the dimensions, and maybe a quarter to a third off the weight. In my opinion, the biggest advantage of the aftermarket power units is the ability to use them with multiple devices— to be able to charge additional devices like a phone or tablet, cutting the number of cords you need to carry, or having one spare for multiple units, or simply spending $10 for a new adapter to supply a new laptop instead of $100 for a whole new unit.

Choosing aftermarket laptop power adapters

1. Check the rating on the power adapter that came with your device. A 15-inch laptop may require 65 or 75 watts; a 17-inch laptop probably requires at least 90 watts. If your power supply isn't up to the task, you won't be able to run, and will run down the battery if it's already running (or at least, you won't be able to run it and charge the battery at the same time).
2. Most aftermarket adapters use a "universal" power supply fitted with adapter tips. Make sure suitable tips are available for your device(s); in particular, the magnetic MacBook adapter will not be available except through Apple. Each tip runs US$8-15; check prices.
3. The "air" adapter often included is for the old EmPower In-Seat socket. This was a standard socket adapted in the 1990s, but is increasingly rare; most airlines now provide regular AC power through a standard universal socket or DC power through an auto "cigarette lighter" socket. If you don't fly in a seat with EmPower, there's no need to spend extra for it.

Product suggestions

I have used Kensington's line for several years and am generally pleased with them. The Wall/Air Ultra Compact Notebook Power Adapter is slim and includes a 1.0A USB socket for recharging a phone or other device. Adapter tips are around $10.

I have no personal experience with Innergie, but they offer a line of compact adapters that similarly come with one or two 1.0A USB ports. They look "prettier" than the Kensington equivalents, but I cannot speak to their durability or suitability.

Before Kensington, I used several iGo products, the simplest of which is the iGo Green Laptop Wall Charger. It appears to be a tad shorter in exchange for being longer and deeper. I left iGo because the Kensington was smaller and cheaper, and I had heard bad reviews of the Green line; however, that was several years ago and I have no new data.

Yet another company is Targus, with a line of chargers; however, these do not appear especially compact, other than the space savings from leaving secondary device chargers at home.