Here is a short list of additional notification icons that it would be great to see added to the existing icon choices:

Car, Truck, Plane, Bicycle (please!), Boat, Motorcycle, Dog, Cat, other animals, Cell Phone, Laptop, Computer, Chef-Police-Fire Fighter Hat, Golf Ball or Golf Clubs, Tennis Racket, Football, Soccer Ball, Basketball. I have a use for 90% of the above. And I think others would too. Thanks for looking at my suggestion!