Some time ago I changed my account settings to screen comments from anyone not on my friends list. It was the only way I could think of to keep the spam from actually appearing on this journal. It still fills my inbox though, and I have to dump it all every once in a while. Today I went looking around for anything else I could do, and found something about disabling pingbacks. I don't fully understand what that means, but I've disabled it and I'm hoping it may help discourage spammers.
The upshot is that I don't want to discourage people from commenting or messaging me through LJ. So, my apologies if I've deleted your comment or message because it was buried in 32 pages of spam :-(.
If any more knowledgeable folks have suggestions for avoiding spam-comments, I'm all ears.