Just read this http://aplus.com/a/father-john-wilhelm-photoshops-his-three-daughters

What other surprises/tricks do you do for your loved ones, using your skills? (design, coding, anything)

For example, an ex-girlfriend pretended her phone was ringing while we were out, she picked it up and said "Yes, he's with me. ... It's in the purse?", then she pulled out a present, saying "It was Santa. He said this is your present."

A few days later, I changed a contact's name to Laponia, and had him call me at a preset time when we were together. I showed her the phone while ringing, wondering who's calling. She already knew the country is automatically shown when it's not local. Then I answered and did almost the same trick, a little more detailed :) She asked me if I built an app just for this.