The DNSBL countries.nerd.dk
Resources for Learning and Teaching
FAQ: POP'ing GMAIL spam - SpamCop Discussion
PHPrbl || Realtime blacklisting for your website || rbl for blogs ...
Openrbl DNSBL RBL Blacklist Lookup
RBL's
Understanding how RBL's work
mailpolice
RBLDNSD
Completewhois Multi-RBL Lookup
Rock tha haus.
A good way to find out if a machine/IP is on any lists
Use for example "dig +short 0.6.61.69.zen.spamhaus.org", see http://www.spamhaus.org/sbl/latest.lasso for blacklisted IP examples
The Spamhaus Project - SBL
Google Groups: misc.legal.moderated
spamhaus.org ???????????