I recall Marc has said he's open to trying something if we can identify it. I've poked around for Invision Community add-ons without luck (not that I'm at all expert).
I think that there are ways to upgrade the site software to get a more effective CAPTCHA, automatically moderate new accounts, etc, but that's up to the admins.
Now there is spam in the Off Topic sub forem, posted by a new "member". I thought members had to be on the forum for some time before having access to the Community section?
To the admins . . . Some forum software has the feature where a new account is a request for approval. You are not allowed to post until you are "approved". I have always disliked this feature but maybe it could come in handy in this situation(?).