Like other people, I'm confused about what exactly "useful" is supposed to mean. In fact, maybe this confusion is the one and only reason people haven't all voted for the same option.
If we're talking about
utility in the sense that philosophers and economists talk about it (in which it is a very abstract concept), then the question makes no sense. After all, I am a human being. Whatever things I may value, I value them only insofar as a human being can value them; the value is "relative" to how much "utility" (that abstract concept) they bring me. So in this technical sense, saying that something has "intrinsic value" is absurd. Value is entirely relative (matter cannot have "value" inherently tied into it in the same sense that it has "mass")---but like Mise said, this is just a truism.
But then there's the more common meaning of "useful." For one reason or another, most people think of factories and cars and cell phones as "useful," but not paintings, music, etc. I don't like this way of thinking, as often it leads people into valuing production and exchange and consumerism for their own sake, forgetting that they are only means to an end. But at any rate, if this is what Prince_Imrahil meant by "useful," then the question actually makes sense, because it's basically asking us if we value the environment at least partly in the same way that we value a great piece of music, as well as if we value animals' lives in the same way that we value the lives of other people. If that's what's being asked, then yes, in my opinion the environment, animals (at least the more sentient ones), etc. have some "intrinsic value" (as well as, of course, being "useful").