HN has a hair trigger about banning IPs that request too fast (sorry about that; we don't have a lot of spare performance), so I wrote something people can use to get their IP unbanned once if it gets banned by accident.
http://news.ycombinator.com/unban?ip=<ip address>
Obviously you have to use it from another IP address, like your phone.
Since there are so few images on HN, there is no reason to have more than a couple connections per IP on port 80.
It will radically reduce your server load and there will be no blacklists/whitelists to maintain.