Yes that would be cute or if you name your custom shep Jane or John then LI and other npcs like Anderson would say it. Beyond that Hannah for space shep's would email him/her and type whatever first name the player put into the system so if you named yours Happy Sunshine Shepard. Hannah would type:
To: Comm. Shepard
From: Capt. Shepard
Happy Sunshine, how have you been? I wanted to let you know I'm coming to your trial and no matter what I will stand by you. I don't care what the media says I won't abandon my son.
Love,
Your mother Hannah.
So obviously you could make that letter really hilarious but it would still be a personal touch by someone who should be very close to shep.
I think you should also kill an assassin somewhere and find a note that reads: KILL HAPPY SUNSHINE SHEPARD:
Description: Human male, light hair, green eyes
Reward: Your own planet and a years worth of supplies
Wanted: DEAD (Good luck)