[falter]

Guys, I'd recommend against using dnsbl.ahbl.org or sbl-xbl.spamhaus.org. Their primary function is to provide a list of Open Mail Relays and email spamming sources, which are an ENTIRE different world than Open Proxies. I don't think that fact is illustrated enough in this thread.

AHBL is particularly aggressive in that they are willing to list blocks of ip addresses. That is, if you have users on a Seattle Area DSL network, and an open mail relay shows up on their network, both that mail relay and your users (or potential users) will be blocked by AHBL.

You guys really need to read and understand the purpose and the usage of these blacklists before slapping them in. Many of these blocklists prohibit the usage of their services in this way. You're unnecessarily hitting services that have finite resources. Don't be so eager to block IPs willy nilly and think you're making a difference. You're not. If your goal is to block users coming through anonymizers, proxies, or even the TOR network, then use blacklists whose function is to only report anonymizers, proxies, and TOR networks. The fact of the matter is that you're not going to see a lot of hits with a blacklist like this simply because not many people are going to register with your site who are actually using proxies.

Here's what I'm using currently:
proxies.dnsbl.sorbs.net
tor.ahbl.org

I don't get many hits, but that's because I don't expect many hits (that's the reality of things).

Again, I like this add-on, I think it's very useful. I'm not criticizing it's usage. All I'm trying to do is help people understand what they're doing a little bit better.