You just can't top this one, Gavin Newsom. United Nations Environment Programme promises to plant a tree for every person who follows them on Twitter. Check it: "UNEPandYou: Remember, UNEP will plant one tree for every twitterer who follows @UNEPandYou by 5 June, World Environment Day. 3 days to go!" Gimmicky? Very. Legit? Um, let's hope. So far, as of 3:35 p.m., they have 4,446 followers. Might you be one more?