I just watched a fascinating talk by Denis [sic] Dutton at TED, 2010 in Long Beach. He makes a really interesting case for Homo sapiens' innate appreciation of beauty being explainable by natural selection. As an ecologist, it's got my mind wandering in all sorts of fun directions, now.
Is our appreciation of beauty just runaway selection based on a sensory bias? Can part of it be explained as an honest badge of fitness? Does "beauty" only make you happy because those who are drawn to it are more likely to have offspring that live to reproductive age? And if you like the feel of a well made tool in your hands, it might actually be a heritable trait.