I'm here to second the question. Today I was trying to read an article on a creative writing website which was linked to me on Twitter. When I tried to access the site I got this: http://i49.tinypic.com/357psib.jpg
I'm an end user of the broadband internet provider and have a fixed IP address given to me by my provider. Like Zeddi has already pointed out, Spamhause blocks a wide range of such IP addresses.
On the Spamhaus website they say that their lists are for outbound email, not http connections. On the CBL (which is one of the lists that has my IP address) they state it even more clearly:
What affect is this listing having on you?
The CBL is intended to be used only on inbound email from the Internet.
If you are being blocked from IRC, Chat, web sites, web email interfaces (eg: you're using Internet Explorer or Firefox to send email) or anything other than basic email with a mail reader like Exchange, Thunderbird etc, the provider of this service is using the CBL against our recommendations. Contact the provider and refer them to http://cbl.abuseat.org/tandc.html and refer them to item 2 and 7.
The PBL list (the second list on which I'm on) sates the following:
Q: Help! My IP address is on the PBL! What should I do?
A: Nothing, in most cases. Read through this FAQ for further explanations.
The first thing to know is: THE PBL IS NOT A BLACKLIST. You are not listed for spamming or for anything you have done. The PBL is simply a list of all of the world's dynamic IP space, i.e: IP ranges normally assigned to ISP broadband customers (DSL, DHCP, PPP, cable, dialup). It is perfectly normal for dynamic IP addresses to be listed on the PBL. In fact all dynamic IP addresses in the world should be on the PBL. Even static IPs which do not send mail should be listed in the PBL.
In short: your plugin is preventing me from accessing the websites for nothing at all. My only fault is using broadband connection. You are using the lists which are not intended to be used as blacklists to block access to the websites, which is a violation of the list provides' recommendations (it should be only used on email, not on http).
To sum it all up. I guess that this particular site is lost to me. I cannot even contact the owners to ask them to remove the plugin or set it up a bit differently. However, I'd like to know what you intend to do about it.