Former vice president Gore spoke at Google a couple of weeks ago (promoting his new book). One of the research projects he mentioned was "spider-goats", goats that are genetically engineered to secrete spider silk along with their milk.

Some details in a news article here: http://www.guardian.co.uk/science/2012/jan/14/synthetic-biol...

Given the value of the silk (and presumably the difficulty in mass-farming spiders), this seems like an attractive idea -- as long as the scientists do the math right and don't end up with spiders the size of goats or something.