Auto Ban IP based on failed captcha/register

That's an interesting idea, although it might make GoAway less "lightweight". It seems to me a good way to do this would be a Trigger and an Action. I have posted in the issue queue for Captcha, to see if there are any plans for a failed captcha to fire a Trigger. Then perhaps GoAway could respond with an Action. But we'll have to wait for more information before anything like this can proceed.

As site administrators may be difficult to always check the visit IPs and block it manually,

I suggest we can add the flood control of IPs, such as when an IP visits too many times in a short period,

then the module would auto add it to the ban list.

I would love to auto ban when bots scan for random exploits and trigger a bunch of 404's.

Update: No response at #1032080: Captcha > Trigger. Moving both these issues to the D7 branch.
This would certainly be useful functionality.