Come on you guys. You know we all wanted to have one of those rings, back then to have cool adventures, and today for our own gain. What else can you do with the power of flame if not working in the metallurgy industry, or maybe rocket fuel science.
Personnally, I'd like the ring of heart. Imagine the implications: from basic seduction to manipulation to finances to psychological warfare. Now that's worth making a movie about!
And as for the big cheese, Captain planet? Just re-imagine him like they did for Galactus in Fantastic Four 2: Rise of the silver surfer.
(ok I know I hated the movie too, but Galactus as a planet-eating nebula instead of a giant was pretty imaginative)