Liberals tend to be higher on openness, and it takes openness to read websites like yourmorals.

In general, most websites that serve "nerdier" people tend to have very strong liberal biases (frequently with libertarians outnumbering conservatives). Conservatives are rare on most of these websites (it's the same case for reddit, digg, slashdot, and scienceblogs readers). Of course, the audience of people interested in social science also tends to skew left.