Spend the day with your dad, go to the local natural preserve, or the park. Take a long walk and just talk about life and stuff. Spend all day with him and tell him how much you apreciate everything he has done for you.
whenever i dont have money and my mom or dads birthdays are coming up i take strips of paper and write stuff like free chore or free hug or a do whatever you want free card. they almost never use them but they always laugh when they find them in a card that is covered in glitter (just kidding about the glitter)
Every Dad has chores he routinely engages is that he is none too thrilled about: Mowing the lawn, dusting the furniture, washing the car, trimming the bushes, cleaning the windows, etc. You could make a coupon book with coupons redeemable for chores.