So, you thought the whole reason to own a DVR was so that you could skip commercials? Think again. Today TiVo is rolling out the Madison Avenue-friendly Product Watch service, which lets you watch commercials on demand. Whether anyone will actually demand to watch these ads remains to be seen, but TiVo has managed to sign up over 70 advertisers, who will provide the service with everything from 60-second spots to hour-long infomercials, which will, in the words of TiVo CEO Tom Rogers, "deliver real, relevant results for our advertising partners while at the same time enhancing the TV experience for subscribers." Ads will apparently include gems such as cooking tips for products such as Kraft's Tombstone pizza and Jell-O, and a Ford ad featuring Penn and Teller. As long as we can delete them from our hard drive, we'll live with the ads -- though we may just archive the Kraft spots to DVD; you never know when you'll need some tips on preparing Jell-O or nuking a frozen pizza.