The EFF suggests constructive direct action against censorship. Here's some other things you can think about, even if you're not a technical person.Right now we are witnessing a monumental shift in the balance of power between states and citizens. One reason we've held on to powerful states is that we have needed them to organize masses of people - the only way we knew to organize was with large, hierarchical organizations. The internet provides us with new possibilities. Wikipedia, for example, is organized with very little in the way of traditional management.
Because the internet allows people to organize themselves in a far more democratic fashion, our need for the state is diminishing (not zero, not even small yet, but less than it used to be). Stateless organizations like Wikileaks that show no respect for any particular government or government at all, but rather consider their allegiance to the "public" at large, really anger governments.
I believe the US government's reaction to Wikileaks results from the shock of realizing this change in its power, and is a desperate attempt to regain it. If it were to succeed, all of our liberties would be endangered.
Be a political entrepreneur
One way to protect our liberties is to actively exercise them. Be a political entrepreneur like Wikileaks - think boldly about how we might use the internet to reshape the way democracy works just as so many companies have reshaped commerce. We don't know what the possibilities are for organizing large numbers of people in a radically democratic way until we try. So try!