Add an introductory message to a friend request

When making a friend request, it would be nice to be able to attach a brief message. This could appear as a specially-coloured Plurk in the recipient's timeline. This feature would help with the problem those of us with private timelines have, of not knowing whether to accept a friend request or not.

The downside is that this could be a way for people to spam the timeline of someone with a private timeline.