My husband works around the clock, too, and I usually try to get him something that I know he loves every time I go out. Sometimes it's something big, sometimes it's little. Sometimes I'll be out and about with the kids and I'll pick up some dinner for him and take it to him at work. He is the type that recognizes that type of gesture. We have food allergies at our house, so we don't have any dairy, peanut, or egg products or anything can contains them at all. So on Father's day, I made him a special gift basket with all of his favorite things that he "can't" have. Like his favorite bottled (in glass) soda, a bottle of V8 smoothie colada, Mother's circus animal cookies, a DVD set of one of his favorite shows, or a favorite movie, Strawberry cheesecake newtons, his favorite gum, his favorite candy bar (reeses cups), movie passes, a gift certificate to his favorite restaurant (even if it's just 5 or 10 dollars, it's at least enough for a dessert)... kind of like stuffing a stocking. It was really fun and he absolutely loved it! He's not usually a very expressive person, but he told everyone about it. He thought it was the coolest thing and I was hoping that it wasn't a dumb idea. You could make your own basket and pay a kid or a delivery service to take it to him at work.
You could also plan a fun date and surprise him by taking him to his favorite place (whatever that may be) and send him little clues every day for the week. If it's taking him to the movies, you could send him a package of popcorn, or a candy bar, or a commercial (coca cola/pepsi--you could probably pick one up at a gas station) paper cup with a love note written in it, lol. Maybe you could do a letter a day to spell it out, I don't know, I'm totally thinking off the top of my head and realizing I need to do something like this myself.
Good luck!