Yes, I completely agree that having them not register in the first place would be preferable, and having them not be able to get a post through at all is another preference. But, I don't set the priorities on plug-in management for these forums (and frankly, don't want to; I have admin bits elsewhere and don't need anymore, thank you). Of course, problem with the first bit is, as mentioned, when you get a better mouse trap you eventually just get better mice. How I manage to deal with it elsewhere, then, is by running modules that simply don't allow the use of the URL tag outside of a very small selection of sub-forums for users beneath a post count threshold. If they can't manage to make the posts their clients want, they just don't post.
There is a level of adaptation going on with these bots here, though. In December we added a blacklist of common spammer terms that throw new posts from new users into the moderation queue; a couple weeks ago a few of the bots started making new posts with simple content like "HELLO THERE" and then editing it once through to bypass this check. Not by any means all of them, but I've noticed a few are doing that now. The blacklist does tend to catch about half to two thirds of all attempted spam on a given night, though; unfortunately, though, I still have to manually review and delete the accounts when I wake up, and it's all in the same queue as the Server Promotions threads, which means those get delayed.
The other measure I could suggest of course is a flat out ban on IPs in most of Southeast Asia. Of course in a couple months they'd probably just get replaced with the Russians anyway, but I'm grumpy enough about the whole thing to just stop caring. The Spam Cleaner button addition did remove a few keystrokes, but it's still far too manual for my liking; it'd really, really be nice if I had an in-line moderation option for spam bans instead of having to open a dialog for every single account individually. Seriously, queuing up 30-70 tabs means I basically can't run anything else on my system while cleaning it, and any other way of handling it takes too long. I ultimately get a lot more cursory in handling other moderation tasks because I'm so burnt out from the endless spambot war. As somebody who can't even cross a room without several paragraphs of exposition, that annoys me a lot too. =)