Animal rights?

I often walk past the animal testing lab in Oxford as it's on the way to my faculty, and it's not uncommon to see animal rights protestors demonstrating outside. Animal rights protestors are especially visible in Oxford, but they're even more high-profile this term, thanks in large part to the declaration of the Animal Liberation Front, the extremist wing of these protestors (who are willing to resort to violence), that even students were not off-limits.

So, finally, someone had had enough, and organised a counter protest, called, rather ingeniously, Pro-Test. You can read more about it here.

Anyway, I was just wondering what an informed Christian view on animal rights might look like. Broadly speaking, humans are of course meant to be stewards of the earth and to care for the Earth, including animals(Genesis 2:15, 19-20). After all, creation is good (as is pretty obvious in Genesis 1). So, there's no way we can condone animal cruelty for the sake of it. At the same time, human beings are especially important (Genesis 1:26-28), imbued with dignity not granted to animals, and their lives must obviously take precedence over animal ones. To that end, animal experimentation might be useful in medical research, which can be used to save more lives. (Although some animal rights group dispute this).

But I was just wondering if anyone has anything to add beyond the rather broad principles sketched above? Are there more complicated ethical issues involved?