I just realized that I haven't spelled out my comment moderation policy.
I have active comment moderation. I know it cuts down on the spontaneity of the comments, because you have to wait for me to log on and approve them. That can take a while because if I'm busy, I don't log in at all. I first set things up this way because I was initially paranoid that I'd be "outed" online, but I keep it this way to cut down on the spam.
I accept all comments that are not simple plugs, with somewhat higher standards for businesses. For example, if you leave a comment that says "great blog! Love, (my link)", you have to link to a fricken' awesome and relevant personal blog in order to be accepted. I will accept commercial comments if they actually add something to the conversation. I like comments on old posts. I like comments even if they appear to be from someone who googled something tangential to what I'm writing about and has an axe to grind. Basically, I like all comments that aren't a blatant effort to drive traffic to an unrelated site. I'm looking at you, college paper ghostwriting service!
It would be nice if I could pre-screen commenters so that regular commenters wouldn't have to wait for me to accept comments. But I can see more technical snafus, so maybe it's best to stick with the slow system.