Blacklist IP database
Is there an open database of blacklisted IP for the Web? With a lot of public web proxy you know... such the blacklist used by the Global blocking of Wikipedia.
You can use Blacklist IP Addresses Live Database from myip.ms -
They have latest Blacklist IPs collected during the last 10 days for use in .htaccess file or in website firewall.
Google has a Safe Browsing API that lets you check against a db of hashed values. It's public and it's encrypted. They have two databases; phishing and malware data in 2 separate blacklists. However, they contain hostnames, not IPs, but perhaps its something you could use.
For blackips (optimized for iptables/ipset)
For blackdomains (optimized for squid)