Wall Warts is a slang term used for power supplies (wall transformers) and are the little brick-like devices that come with almost every electronic device. So why do I say they are like socks? Well, like socks, they seem to lose their mate and you end up wondering where it belongs.
Socks have a habit of getting lost for a period of time (typically around laundry day) but eventually show up and can be reunited with it’s mate (or one that looks similar). The same can’t always be said for wall warts. These are the ones that have no identifying information about where they belong and to make matters worst, may actually have a plug that would fit a number of devices. The fact that the plug fits, means it could supply the wrong power (voltage, current, polarity, AC/DC) and possibly destroy your device. (See AllElectronics.com for some examples of wall warts.)
This is a problem I’ve seen for years and I thought manufacturers were getting better identifying their products. Just the other day I bought a Maxtor 750 GB OneTouch4 external USB drive and it came with a small power supply. On the power supply was this information: “Sunny Switching Adapter; Model: SYS1308–2412–W2 … OUTPUT: +12V 2.0A …” It also showed a symbol indicating that the center connection was positive. The back of the Maxtor OneTouch drive had no voltage or polarity information so if I was trying to match up this power supply to it’s mate, I would be taking a gamble if the plug just happen to fit. This power supply uses a very common power connector and I know it’s fits at least four other devices that I own. I wonder how many devices have been destroy because the wrong power supply was plugged in? Would you take the time to research the power requirements of your device before plugging in an unknown wall wart if the plug fit?
I’ve developed products before and totally understand why manufactures do this. They develop a product that uses a common power source (i.e., +12V DC, 1.0A, positive center) and order an off-the-shelf power supply from China. It cost more to private-label the power supply, so they decide against it to keep down the cost. There is nothing stopping a company from offering a power supply with the same power connector but with a different power output (i.e., +5V, 0.5 A, negative center) and shipping that with a different consumer product. The consumer is the loser when he/she tries to mix and match loose wall warts and with their tech toys.
I do see a trend that I think may help. It’s the move to USB. More manufacturers are using the fact that the USB connector supplies a standard 5.0 VDC at 0.5 Amps. I said I think it may help because a lot of newer USB devices need more than the 0.5 Amps supplied by a standard USB connector (my Zune requires 1.5 A and my Android G1 phone needs 1.0 A). At least you have a fighting chance and may only damage (overheat) the power supply if your device needs more juice.
I would love to see manufactures label their power supplies to help out the consumer. I can’t believe printing and placing a sticker on the power supply to identify the manufacturer before they ship the product would be that costly.
I make it a habit to add a label to every wall wart before I start using the device. I have a Brother P-touch labeler and find it’s very handy (and fun) for things like that. I even add labels to wall warts that has been re-branded because I generally find the information is too generic (i.e. Maxtor) or hard to read when I’m looking to remove a power supply from a power strip under a desk with very little light. (I won’t mention that I have aging eyes too.)
Another reason I do it is because it’s a nice feeling knowing I’m organized. It’s wonderful seeing that little label showing me my Android G1 power supply after digging it out from under a foot-high stack of papers and unpaid bills. 
73’s, Tom