Steve Chen, left, and Chad Hurley, are taking over Delicious from Yahoo.Credit...Jim Wilson/The New York Times SAN MATEO, Calif. — Chad Hurley and Steve Chen have some experience with turning a small Web site into Internet gold. In 2006 they sold their scrappy start-up YouTube to Google for $1.65 billion. More recently they picked an unlikely candidate to be their next Web sensation: a Yahoo casto