They are especially good for family genealogies containing anything and everything that you want to remember about a person: images of old photos, newspaper cuttings, correspondence, family trees, memoirs, all connected together by clickable links or images that will take you quickly to other parts of the DVD that interest you.
(Note: this is not live!)
Most clients are happy to save important files to garden-variety DVDs available in city stationery stores. Verbatim is a label with a good reputation - at the moment. On average they may keep your data safe for about 10 years. If you use a DVD or USB stick for your genealogy it will pay to move it to other forms of storage over time. M-discs (available as standard DVDs) have been rigorously tested and are agreed to have between 100 and 1000 years of life, but they are expensive and a supply chain has to be found. External Hard drives and solid state drives are popular for storage and reliable in the short-term. They may last a decade or two if stored unused - maybe 3-4 years if on a device in regular use. USB sticks are good for moving digital files around but are not reliable storage devices. Magnetic tape is still around, but expensive. Archiving options are in flux. For a good article on your archiving options go here
An audio book put on CD as a playable mp3
A book converted to PDF and saved to data DVD
Song tracks converted to mp3 from vinyl LP and burned to an audio CD
A pipe tune composed, recorded and burned to CD for a Japanese Professor of physics
A photo slideshow prepared for a family funeral