I'd be interested in [Leave a list of fictional characters in your journal that you would love to get a message from. It is your friend-list's mission, should they choose to accept it, to write you an in-character "letter" from a character on that list [or other character--these are simply "guidelines!" :D]. Then they post their own list in their journal and the process continues!] But more interested in writing letters for other people. So...comment as a character I know that you'd like to get a letter from. I'd be curious.
Though also and perhaps more interestingly...yoinked the idea from skaryma a while back to make PostSecrets for fictional characters and never got around to it. Feeling unoccupied this evening, so why the hell not...