Rally to Restore Sanity and the March To Keep Fear Alive. And, yes, there's an iPhone app for the both of them.
The Rally To Restore Sanity And/Or Fear [iTunes link] is free in the App Store. Our Android bretheren also has this app in the Android Market.
I uploaded a picture of myself and hopefully tomorrow it will be part of the photo stream.
If you would like to see if there is a rally in your local area, check out the link here.