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.
Jonathan Haidt, a professor at UVA, runs an online lab with quizzes that will compare your moral values to the rest of the population. I have found the test results useful for avoiding the typical mind fallacy. When someone disagrees with me on a belief/opinion I feel certain about, it's often difficult to tease apart how much of this disagreement stems from them not "getting it", and how much stems from them having a different fundamental value system. One of the tests alerted me that I am an outlier in certain aspects of how I judge morality (green = me; blue = liberals; red = conservatives):
Another benefit of these quizzes is that they can point out potential blind spots. For example, one quiz asks for opinions about punishment for crimes. If I discover I'm an outlier w.r.t. the population, I should reconsider whether my opinions are based on solid evidence (or did I see one study that found tit-for-tat punishment effective in a certain context, and take that as gospel?).
Extra reading: Haidt wrote a WSJ article last month that applied the learnings of these moral quizzes to better understanding the Tea Party.