Love this idea! Get an email address for your kids when they are born and over the years send them emails, pictures, memories, etc. Then on their birthday, give them the password! Absolutely going to do this someday!
Display your babies monthly photos from the first year of their life at their first birthday party. I had a floral and pink themed party for my little girl and I displayed the photos above the drink bar. It made getting drink of lemonade even sweeter!