The most practical way to implement this IMO would not be in game, but through the main royals website. Add a "Buddy List" tab along with Char Fixes and Acc Settings. Since all the logs are already on the server, it wouldn't be too bad.
It might be an interesting idea to have sort of a ~lastlogin <ign> command. It'd be helpful for those of use looking for friends to complete transactions/train/etc. It may also help decrease amounts of inactive users in guilds as well as the visual bug of someone being online when not. Perhaps maybe it could display something like "User was last logged in on DD/MM/YYYY and was active for X minutes." "Active" being how long they were connected for.
