Tor is defiantly the way to go to be anonymous on the internet. This may not be of use to you, but I read an article about IP's being taken from VoIP
programs, Skype specifically. Their IP's were then DDoSed. This was happening a lot to professional Starcraft 2 players, which was causing them to lose games. There are a few fixes to this, like setting up a Socks server, or forcing Skype through a proxy.