Question: Once upon a time, in a land not so far away, there used to be this thing called Isyndicate that had this cool service where you could add sounds to your web page. Isyndicate is dead. Is there another service like it?

Not exactly. However, there's an API that's been developed to replicate the Beatnik service that Isyndicate used to offer.You can view a tutorial on how to add sounds to your web page by visiting this demo of the API in action at Sonify.org.