To stand in solidarity with the Iranian election protesters.
Woodrow Hill has two excellent posts here and here about why it's important to blog about the protests.
Andrew Sullivan's blog has frequent updates from insider sources, and Twazzup.com has up-to-the-second tweets from Iranians at the scene as well as people all over the world.
This is history in the making, and for possibly the first time ever, the mainstream media is solidly behind the curve. Bloggers and Twitterers are taking up the slack, giving eyewitness accounts, flashmobbing help to the injured. This is amazing, this is history, this is full-out rebellion against fascism, and the internet is the voice of the revolution.
Take note: The protesters in Tehran are setting an unbelievable example of bravery, and they deserve our support however we can lend it.