As part of fighting with spams in my side project Bulkfeeds (The site is to search Japanese blogsphere and is currently only available in Japanese), I started my own URLBL DNS service!
The service postfix is
rbl.bulkfeeds.jp and here's how to lookup spams: if your comment/trackback includes URL http://poker.example.com/poker.html, you have to lookup poker.example.com.rbl.bulkfeeds.jp. If the URL is blacklisted, it'll return 127.0.0.2 and otherwise it returns NXDOMAIN.
If you run Movable Type 3.2 with SpamLookup (which is on by default), all you need is to add
rbl.bulkfeeds.jp to "Domain Blacklist Services" of SpamLookup configuration. (Example Setup)
Forwarding your splog data with MT
Since 3.2, MT has a nice default plugin SpamLookup to lookup spam comments and trackbacks pretty effectively. But by default, these spam comments and trackbacks are just junked, which looks like a waste of precious information. So I developed SpamSubmission plugin (svn is also available), which forwards URLs found in spam comments and pings to the Bulkfeeds DNSBL service, using its submission API.
Here's how to install: just drop the SpamSubmission directory into MT plugins directory, then go to SYSTEM OVERVIEWS > PLUGINS and click "Show Settings" for SpamSubmission plugin. Choose "TypeKey API" as Auth Type and enter your TypeKey identity, which is required to avoid Blacklist pollution (Example Config).
Submitted URLs are periodically and manually scanned with our splog filter and reviewed by me (to avoid Blacklist pollution), then reflected to the DNSBL service rbl.bulkfeeds.jp.