PeerGuardian

PeerGuardian is an application used for people who are using P2P services and want to block IP addresses belonging to corporate or government bodies, usually to hide their online activities for whatever reason.

This app is also good for blocking some 'bad' addresses such as those from advertisers, spyware and spammers trying to contact your computer.

If you do use this to block advertisers you should keep in mind that your favourite website could be replying on the ads to remain free and when activated advertising spots such as banners will show up as "page could not be found" which may be more annoying than the ad itself.

If you use this, you have to update often to keep the database of IP addresses up-to-date and also know when to disable or permanently allow some IP addresses for example Mysapace uses servers with IP addresses that are on the block list so you either have to allow always for the IP number to contact you or disable the protection, this will also be the same when trying to view government sites such as public transport sites so keep in mind of that when using this little app.