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.
Nice activism, BillF!