Tor is an open source project that allows users to utilise the Internet anonymously through the use of something along the lines of distributed proxies - the Onion router network. Privoxy is more of a local web proxy that, when configured correctly, can protect your privacy by filtering such information at the source. Together they are an effective and user-friendly (but not necessarily perfect) solution to preserving your anonymity on the Internet.
If you manage websites that involve user registrations, I'm sure you have come across users who use services such as mailinator to register. While these services are definitely handy, the users who use them generally tend to be spammers or those that don't necessarily plan to stay on at your website. The following is a list of sites / services / domains that provide services similar to mailinator, and have found their way into my block list.