I use a [Brother P-Touch][1] with the [laminated extra-strength adhesive tape][2] to label all of my "wall-warts" with the device it powers. All of the cables are coiled and wrapped with [Velcro One-Wrap straps][3]. Since the wall AC power and standard (e.g. usb) device cables tend to have common connectors, I just throw them all in a [Really Useful Box][4] labelled "CABLES"; The power supplies all go in a separate box.
I've tried using a silver Sharpie pen, but found that the markings can be rubbed off and, importantly for me, in dim spaces (e.g. behind or under cabinets) the low contrast makes them very difficult to read.
![alt text][5]
[1]: http://www.brother-usa.com/Ptouch/Ptouch_Desktop/
[2]: http://www.amazon.com/Brother-Black-White-strength-TZeS211/dp/B004I2LW9O
[3]: http://www.velcro.com/index.php?page=consumer-products-straps-and-organization-one-wrap
[4]: http://www.reallyusefulproducts.co.uk/usa/html/onlineshop/rub/b17_0litreUS.php
[5]: /upfiles/photo.JPG