16 year old boys, depending on their development, like things that they can display in public, like clothing (hats, shirts, jackets, etc.). Also consider a gift that is special between the two of you, like a CD that the two of you can enjoy together.
16 year old boys do indeed care about there appearance but they are also insecure!!!! So make sure that with whatever gift you give him, you point out some of the things you love about him and how he makes you feel special and safe. They want to hear that we need them, they need to feel useful!!!!