Anything we can think of, because I see a great holloween decoration. Puts some tank treads or even spider legs, and tweak the MP3 sounds, and you got one hell of a holloween decoration.
Ummm, does the head move or tilt? Maybe give it some movements so that when it is reading the card, it will look up or at her and tilt its head. (Non creepy like)
You could run an RTC and make it say "Happy Valentine's day" etc for a number of significant days in the year. You could also add a LDR so that if it suddenly gets light at around her wake-up time then it could say "Good morning" or similar. Not every day, perhaps, just every now and again.Also, if there's an IR receiver and she has a TV in the room then can you program it to recognise the "on" TV signal? He could say "Hey, can I watch too?" occasionally.
VOICE RECOGNITION!!! Have it so that she can interact with it. Have it respond to certain words like "Hello" or "Winnie" and have it respond back with a preset library of words.
You can maybe look into EasyVR.