Not sure if this has been requested already, but even if it has I think it is worth repeating. Currently there are only 2 ways to add a recipient for PMs: 1) Buddy List menu, or 2) manually typing in a username, which assumes you know what it is and how it is spelled. It's this second method which I find most difficult as I often forget the actually spelling of some usernames.
I would like to have the ability to click on, for example, a "To" button which takes you to the "User List". And, once there you can do a search and add one or multiple names using the "Ctrl" key... a feature commonly seen in many e-mail clients.
Thanks for giving this some consideration.