As Kevin said, most of your devices probably use the same cable (the iPods might be the exception). My wife and I each an iPod and an iPhone and the same cable can be used on either device so I keep one sync cable by the computer the others are plugged into the power blocks where we charge our phones. As to cameras I don't know of many cameras anymore which don't use the mini-USB standard. So realisticially you really only need 1 USB cable for getting pictures off your cameras.
The only wild card would be your Blackberry and I know many of those use a mini-USB connector (just like your cameras) so the same cable might be used for this one as for the cameras. If however you feel the need to keep all the cables around as Normand said Avery labels work well or one of those pTouch label writers work well as well (we use those where I work).
Brian
"My father was very sure about certain matters pertaining to the universe. To him, all good things - trout as well as eternal salvation - come by grace and grace comes by art and art does not come easy." Norman Maclean, A River Runs Through It