www.notonedamndime.com
This kind of stuff is only useful in the sense that it keeps people who are already established in their opposition feeling like they belong to a community. It will have absolutely zero effect on the Bush admin directly, and the fact that there is a substantial portion of the population (roughly 40%) that is virulently opposed to Bush is already widely known and not news, so it won't even be a media event.
If it became a media event, it could easily be spun as something that hurts small business owners and demonstrates "typical liberal arrogance."
Everyone would be better off wearing shirts that say "I'm here, where is W?" and volunteering at a homeless shelter or something.
But really, what liberals need to do is stop thinking in terms of public protest and role up their sleeves and do what the Republicans did after Goldwater. Start at the local level, build an infrastructure, and think in 50 year time-lines. Heck, it only took 16 years to get from Lyndon Johnson's win in 1964 to Ronald Reagan's in 1980, and we've essentially been living under a Reaganesque system ever since...