Petition the government online!
I think the petition site at whitehouse.gov is a great thing. Petitions that receive enough digital signatures (25,000) are guaranteed an official response. Good for the people to be able to post their views to the right audience (as opposed to a blog which no political decision maker will ever read 
), and good for the government as a real-time indicator of public opinion.
Please support my petition for the government to convert its fleet to electric and biofuel-powered vehicles (beginning with the post office): http://wh.gov/Tbf
Or create your own petition at https://wwws.whitehouse.gov/petitions#!/