Eeew. Give 'em the purple finger for me, will ya?
Depending on your state, there likely is one or more locations allowing you to give them the purple finger in person.
Additionally, or alternately, to going to or organizing a rally/counter-protest, please consider writing letters to the editors of your local papers, starting about a week before the protest, pointing out that for over a year ANSWER's website included the statement that "the anti-war movement here and around the world must give its unconditional support to the Iraqi anti-colonial resistance." ANSWER's leaders are not anti-war. They just support the side fighting America. They support the people blowing up our troops in Iraq, intentionally killing innocent Iraqi civilians, and beheading American civilians.