It’s hard for those who like to maintain anonymity and privacy on the internet, especially when downloading files from torrents. PeerBlock is designed to help with that: here is the straight goods from their FAQ:
What is PeerBlock? The short version is: PeerBlock blocks “known bad” computers from accessing yours, and vice versa. Depending on the lists you have it set up to use, you can block governments, corporations, machines flagged for anti-p2p activites, even entire countries! Whether you’re sharing files with Bittorrent or just surfing the web, PeerBlock can help protect you from the bad guys.
Highly recommended for anyone downloading bittorrents: works great on Windows 7, Server 2008 and Windows Home Server and Vail.