At my standard glacial pace
In response to Katrina, Eszter Hargittai at Crooked Timber offered an incentive for disaster relief donations - this was enough to get me to send a few bucks to Mercy Corps. Having received the book (which is full of neat examples of symmetry), I've reacted at my standard glacial pace by sending them a few more bucks for Pakistan earthquake relief. All of which I note by way of encouraging people to give a little, esp. in view of the geopolitical situation.