Nothing too extravagant, but I will make a card and sign it from LO and get a sentimental gift since it's his first fathers day.
I am thinking of something like this with our son's name on it
http://www.etsy.com/listing/98004927/custom-pet-id-tag-dog-tag-riley-in-mixed
He is totally sentimental and I think he would totally gush over it. I love it