Quote from OrionShockgood idea, but srsly... sharing accounts is not allowed as per ToS (generally). So please remove that aspect from the good idea :)
I know it's usually against the ToS however I have a few friends that have kids that play the same account which is to my understanding allowed as long as the kids are young enough. I was thinking of them specifically when I thought of the feature.
However now that I think about it in more detail the addon would have to be setup that way anyways because there are no global variables per server and per alliance/horde. So regardless having multiple lists would be a necessity for anyone that plays on multiple servers or horde and alliance. Granted I could always hard-code a single list per server per faction but that could result in tremendous amounts of data that would be saved over and over for renamed or server transferred characters, not to mention lost contact lists.
An additional feature I've thought about adding is a rating system (1-5 star) for raid performance (per toon/player/both?) and then maybe a way to share your ratings with other people with the addon (much like gatherer)... obviously with options to turn auto-sharing off.