Having received a nice link from my favorite blogger, I'm feeling pretty excited. I hope I keep saying useful things!
One thing I've been doing in spare time lately is surfing minor right-wing blogs and politely correcting misperceptions about Democrats. (I look at this as a reasonably successful sortie.) I do this partly because attacking a straw man is probably the most effective argumentative fallacy in politics. You convince your audience that your opponent is a dumb or evil person with a dumb or evil view, that they don't need to read any more about the opposing view, and even that the opponent's accurate presentations of his view are dishonest flip-flopping. The echo-chamber tendencies of the blogosphere cause straw man arguments to spread rapidly -- the less contact you have with sophisticated expositors of the opposing argument, the less likely you are to make contact with the real argument you're attacking.
(On the non-straw-man side, it's also good to spread facts that will keep right-wing fantasies from raging out of control. It would've been nice to quickly debunk the rumor about the embed planting the "hillbilly armor" question to the soldier, which was running throughout the right-wing blogosphere a week ago. Unfortunately I saw the article too late.)
I don't have any illusions that my actions immediately convert anybody. But there are some things that I hope to accomplish. For one thing, our opponents will put more effort into being intellectually honest if they're aware that there's a liberal out there in the audience, ready to stop any straw man action they try to pull. Remember that there's one thing that conservatives will regard a liberal commenter as an authority about -- liberal positions and arguments. While you might not make much headway on "How bad are things in Iraq?", you're likely to do much better on "Is Howard Dean a radical pacifist?" or "Do Democrats love Yasser Arafat?"
This goes without saying, but politeness is a prerequisite for this kind of work. Putting a friendly face on liberalism is very valuable, and being more polite than your host is one way of doing that. The only thing that one should show anger about, I think, is a drastic misrepresentation of liberal positions. (For example: when it's claimed that our attacks on neocons are actually covert anti-Semitism.)