Not sure if this has been suggested already, but... here it goes ^. ^
On the Friends List, you know the option "Remove" when you click on a friend's name? There should also be a "Comment" option, where you can make a short comment explaining maybe how/when you met them, info about their character when you first friended them, things like that. It would be helpful (maybe o .o) if you had loads of friends, because it could get a little confusing.