I became a premium member in large part to support Geocaching.com because of the enjoyment I get from its services. Considering all of the $$ for gas, gps, bug spray, etc. the cost of a premium membership is a small part of my geocaching expenses.
10/10/10 has also been selected by 350.org to be the day for the 10/10 Global Work Party to draw attention to the need for action on climate change. I suspect that some of the ideas being promoted here would also fit with the 350.org theme and could be registered there as well. Learn more at http://www.350.org/workparty-ideas.