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 castoff. The men are trying to inject new life into Delicious, a social bookmarking service that, in its time, was popular among the technorati, but failed to catch on with a broader audience.