Two small ways to help Iranians risking their lives for more freedom, one useful and one symbolic.
1) Change your Twitter location to Tehran, and your time to GMT +3:30. The State Security Services are searching Twitter to find protesting bloggers. Adding more hay to the haystack will make it harder for them to find the needles.
2) Change your Twitter and Facebook pictures to make them green in solidarity with the protesters.
It's remarkable how useful new media, and especially Twitter, has been in not only letting the world know what's going on inside Iran, but also helping protesters communicate with each other. I know people like to mock Twitter as just bloggers telling each other what they're eating, but any tool that makes it easier for people to communicate makes for a better world.