Like most people, I'm saddened to hear that the Yangtze river dolphin has in all likelihood become extinct due to human activity. It's a sad commentary on industrial capitalism, etc etc.
But let's not kid ourselves. This thing was revolting.
It's nearly blind, with only rudimentary eyes. It smells like sewage (mostly because it lives in the highly-polluted Yangtze). It's not cute like Flipper - not in the least.
If I had to choose a species to obliterate, this might be it.
UPDATE II: For more debatably ugly or cute creatures, see Ugly Overload.
UPDATE: The comments have brought up some interesting ideas, and I left this response, but since it's so long and apparently not obvious (fair enough, I say), I'm going to repost it here.
It's funny how this thread has turned out, because it's actually brought up a lot of Big Interesting Questions, for which I think I have somewhat unorthodox answers with which most of you might not agree, but probably not in the way you're thinking.
Don't get me wrong, I do think it's horrible that this animal has gone extinct. It indicates trouble for the future of human existence, and it's made a bunch of people sad. But I don't place any particular moral value on the existence of any species (even humans really, but I'll get to that in a bit). I like dogs and cats and sharks and lobsters and cows and earthworms, but I don't think that their particular manifestations are important in any moral way. Some of these animals I like to hang out with and pet, some I like to eat, some I just think are cool, and others are integral to making a world that I can live in. Note that these are all pretty self-serving reasons to like biodiversity. Being as atheistic as I am, though, and looking at the universe as open-ended, I think that the only really sensible or realistic way to look at the environment is a vehichle for human survival, human pleasure and human progress. Just like I reject the idea that having an abortion is screwing with fate and murdering a human being, I reject the idea that there's any particular form our environment is supposed to take in any moral sense. Think of it this way: would the world be worse off if cows had 8 eyes instead of 2? Why?
My allegiences are always with people, and always against human suffering (when I'm being consistent). This is due to my admittedly limited ability to understand the moral reasoning of non-sentient beings, which has led me to a short-hand of believing that there just isn't any. If causing the extinction of all fuzzy animals would, say, end rape and have no consequences beyond a net loss in my daily experience of cuteness, I'd be all for it. This is of course not possible, any more than it is that we need to decide between human existence and the Yangtze river dolphin's. And I think it's important to err on the side of open possibilities, and preserve the things that we like for whatever reasons (spiritual, aesthetic, entertainment, medical) we come up with. This dolphin has been called a river goddess, and though I don't share in valuing it spiritually, the fact that others do is important to me and one of many reasons to (have) work(ed) for its preservation.
But, as you can see, if it were up to me, if there were a fill-in-the-blank species up on the chopping block that I had to choose, according to my values and whims and having little to do with reality, this guy is one of them. I can think of others - say, mosquitoes.
But I do realize the reasons why this is absurd, and that's where the joke part comes in. To me, one of the most compelling reasons to preserve the environment is that we don't know what the consequences will be, and as far as we've shown ourselves, they're usually pretty bad for us. There are plenty of consequences of environmental irresponsibility I'd like to avoid, but my point is that if we know the consequences of a choice, I want to err on the side of human health and happiness. And I want to know why we shouldn't if others disagree with me.
Even if we were to wreak destruction on the Earth and cause our own extinction, the world would go on living or not with no one around to care. The pain and suffering that would be experienced would be rued by all, but when it's over it's Over. (I should point out that thought it might be kinda funny to wish extinction on human beings, it's been done before, and no would be around to get the joke).
Maybe this is taking atheism further than most people are willing, but it's where it's gotten me.