I don't know if SWAMP THING is still being published. But at one time (if you can believe it) Greenpeace was negotiating with DC to make him a spokescharacter for their organization and the environment.

I always found him a much more interesting character than Marvel's competing MAN-THING. Man-Thing has no personality or dialogue, so it's very difficult to script him in a consistently interesting way. He's more interesting as a background character that plays off other more versatile characters. I'm amazed he can sustain a series, or have a fan following.