I would say something you guys don't do on the regular. If he's a gamer, buy him a video game and try playing it with him. If you're sexually active, find something to spice up your sex life. You can cook his favorite meal for him. You can do something simple like maybe waking him up with a cup of coffee (if you sleep over), a back scratch and massage, etc. These are just things my girlfriend does for.me that I appreciate :).