From Telecomix Crypto Munitions Bureau
You might be interested in blocking large chunks of IP-addresses to keep the more disgusting creeps away.
 List of blocklists
- Creeper - Swedish government agencies and other nasty organizations
- Some list of ip-blocks of companies etc - International
- Überwach - a German Creeper-clone (link to the blocklist)
-  - "I-Blocklist is a site dedicated to the creation and distribution of IP lists for use with IP blockers such as PeerBlock, PeerGuardian, Moblock, and iplist." (quote from their page)
- Av Tracker - Antivirus company/researcher tracker by Peter Kleissner
- Authority Netblock Blacklist - the Cryptoanarchy.org Authority Netblock Blacklist (a collection)
- ftp:/ 1a6e /ftp.ripe.net/ripe/dbase/split <-- RIPEs official downloadable mirrors of all their WHOIS-information
- Mirror of RIPE, ARIN, etc, Awesome because the search actually works.