The Proxomitron. It's an interesting little web-proxy that is programmable. For you programmers, imagine having a regex search/replace set of filters that were applied to your web requests or to data you send out to the web. All of a sudden, you have the power to remove annoying Midi background music. Or the ability to alter an element on a site's stylesheet (why did they pick that color anyway?). Or perhaps you might use it to filter out some objectionable words/phrases.