Setting up Anonymous Squid Proxy on OS X For Iran Protestors

Caveat: Running an anonymous proxy entails risks to your own security. Don't do it unless you (think) you know what you're doing and are willing to take on the risks, including, but not limited to attacks by the Iranian government and any other jerks.

Extra Future has a really good article with good bits of information, including a filter list of Iranian IP addresses, and being tricky with the default ports.

Also: DON'T just post the proxy address to #iranelection. See BoingBoing's Cyberwar guide for Iran elections, particularly:

1. Do NOT publicise proxy IP's over twitter, and especially not using the #iranelection hashtag. Security forces are monitoring this hashtag, and the moment they identify a proxy IP they will block it in Iran. If you are creating new proxies for the Iranian bloggers, DM them to @stopAhmadi or @iran09 and they will distributed them discretely to bloggers in Iran.