Since i'm using Linux all the time lately, it doesn't mean that i'm offline from instant messaging-based communication. I use Pidgin for my daily application for instant messaging as it supports multi protocol (even though i usually login only to YM protocol).
Once nice thing that i like in Pidgin besides the openness of the application is that it's easier to move one person to another group compared to Yahoo Messenger. In YM, you will have to drag the person to the correct group. This is easy to be done, but what if your friends are way too much? You will have to drag it way down below / up too long before you reach the group.
Pidgin offers a nicer way, by offering a menu to move a person from one group to another group. All you need to do is right click the person in the Buddy List and select Move To > and it will show you a list of all groups you have. Just click on the group you wanted and bingo... your contact has been moved to another group. As simple as that.
I believe that Yahoo team can do this and i hope it will be integrated in the next Yahoo Messenger 9