There is a March on Washington scheduled for 15 September2007.
It is an anti-war demonstration that will have associated actions for a 7-day period beginning on the 14th. Here is some text from the organizers' site:
A broad spectrum of national groups have united to mobilize for a massive fall anti-war mobilization called the Days of Action. September 15-21 will be a major showdown in Washington, DC at the very moment that the Petraeus Report is released and Congress takes up spending over $100 billion to prolong the war. Launched with a huge March on Washington on September 15, led by veterans who have returned from Iraq, there will be seven days of actions to send a shockwave through Washington and the nation with the reverberating demand: End the War Now!AirAmerica's Thom Hartmann exemplifies the belief of many: that massive grassroots civil action will take place in the blogosphere, in phone-calls, by email, and talk radio, and that in this new era, demonstrations are not where change will happen. Hartmann has been a part of Leftist activism for a long time, has been a steady, reasonable, compassionate, impassioned presence at AirAmerica, and seems to know his stuff. I find him credible.
Something like the planned September 15th March could work, though, if it is executed in a way that cuts through the shallow biases of most major news media outlets and thereby makes an impression on members of Congress and on the White House. To be effective it will have to look something like the vision posted here. The target audience must be properly understood to be the groups just mentioned , not the American populace at large who are already convinced. This march could get a fair hearing for that American majority message, thus far mostly ignored by the DC chattering classes, the Congress, and the White House.
If the actions devolve into a lawless messy spectacle, the target audience will be alienated and the energy going into the event will be wasted.
I don't have plans to attend, but I will be observing with interest.
Update (20:38): I just saw fine print at the bottom of the march site referencing ANSWER Coalition.