I've had the same problem—I'm VERY free with giving out my LJ username (not that it's hard to guess: it's
http://xella.livejournal.com X);; and a lot of 'tards from school and elsewhere like to be cruel to me online as well as off.
It used to be that if you deleted a comment by a given person, you were given the option of blocking that user, only when it was an anon comment, it would be blank. I found that it still worked... but it doesn't anymore.
My suggestion is to turn of anon comments for a
few days... it might be necessary to do so for a week or more, depending on how frequent your particular crazy is. It'll be nasty for those friends who do comment anonymously, and for some reason can't get one (under 13, perhaps? Coz' I know the LJ invite system is gone, thank the gods @o; *was getting so many "hey can u give me a lj coed thx!!!!111eleventyfork" emails because she's a permament account*), but as LJ won't take any steps for you with anon harassers (see
here if you haven't already) you're going to have to do it yourself.
I think the above link (FAQ #109) has a link to some steps you can take to find and report to their ISP directly. My advice is that if you take that route, be firm about what it is you want—their abusive behaviour to stop—and make sure that their ISP at least
warns them that this is a) inappropriate behaviour, and b) lets them know that it won't be tolerated. Hey, they might even give you contact information so you can do it yourself.
Because as far as I~ see it (and their ISP should see the same way I do or they're stupid X3;) online abuse is no different than sending anonymous letters through the mail—it's ABUSE. Plus the raping cats thing... that's like a federal offense, non? (Not to mention absolutely enraging =D;;) And if you're not going to say abuse, you can still say spam—coz' they ARE spamming you and that's not cool.
As for the LJ cut...
<lj-cut text="What the cut will say">The text behind the cut =D</lj-cut>
"text=""" can be left out if you just want the default whatever, I believe, but people tend not to click links that say "Read more..." Oo;;
