Comic Book Resources' Lyin' the Gutters says that one of the writers of the Constantine movie is working a film adaptation of Alan Moore's run on DC Comics' Swamp Thing, called "The Green."
There's no word on a Constantine sequel, however, and the idea appears dead in the water.
The 1982 Wes Craven film had its own charm, mostly on the appeal of love interest Adrienne Barbeau, but the concept could use an updating for the 21st century.