Stay Abreast
One of the best parts of the website redesign for the National Audubon Society was the chance to get playful with some of the site's copy, especially around calls to action. For social sharing of support options, we came up with the tagline "It's the least you can do" early on, and were pleasantly surprised to see it make the final cut. That and other decisions around language have helped soften and conversationalize the content for what was traditionally seen as a stuffy, old-fashioned organization.
The email sign-up, "Stay abreast of Audubon", complete with robin redbreast visual, is still my favorite, though. :-)