Big Brainz has addition/subtraction, multiplication, and division. My kids loved it (and my 6 year old learned all his multiplication and division facts over the summer!). DS would never have tolerated flashcards or more boring fluency programs. He loves the video game aspect of it. You can get free versions or pay to rent deluxe versions for multplication and division (no deluxe for addition/subtraction).
Another free one is Xtra Math, but I don't like how they teach addition/subtraction separately rather than as number partners.
