The incomparable Electronic Frontiers Foundation has a great web site explaining how you can directly help Iranian internet users: Set up a TOR Bridge or a TOR relay.

If you understand what that means, go to the link RIGHT NOW and do your part to make the world a better place.  If you are unfamiliar with "TOR," here is the brief summary from EFF:

Tor (an acronym of "The Onion Router") is free and open source software that helps users remain anonymous on the Internet. Normally, when accessing websites, your computer asks for and receives a webpage out in the open, a process that exposes your IP address, the URL of the website, and the contents of the site, among other information to third parties. When accessing websites while using Tor, your computer essentially whispers its requests for a website, to another computer, which passes the request on to another computer, which passes it on to another computer, which passes it onto the computer where the website is hosted; the reply returns in the same, chain-message manner. The whispers are encrypted, so that neither outside authorities, nor the computers in the middle of the chain, can tell what is being said, and to whom. And the website itself does not have your IP address either.

Internet users in Iran are using Tor to both (a) circumvent censorship systems and (b) remain anonymous while reading and writing on the Internet. Both are critically important to the safety of protesters, many of whom fear retaliation from the government. Preliminary reports indicate that use of the Tor client in Iran has increased in the days after the contested election.