If no one notices, you should bake yourself a birthday cake, light the candles, bring it into the living room, sing happy birthday to yourself, blow out the candles, and serve them cake. I'll bet they remember next year.
I can never stay annoyed with him for long anyhow. He remembered today...and only a day late! So I got my cake and didn't even have to bake it myself. Usually he'll randomly buy me something in the middle of the year and say, "Happy birthday! In case I forget..."