Looking at Star Wars (particularly the prequels), Obi-Wan Kenobi claimed that Anakin Skywalker was destined to bring balance to the Force. However, what does that mean? If the Jedi really wanted balance between the light side and the dark side, why didn't they try to form a coalition council with the Sith? It seems as if their idea of balance was eliminating the dark side altogether. Mind you, I did like the theory I heard recently: Anakin brought balance to the Force by killing all the Jedi and all the Sith!
Forming a coalition is the basic concept for the Transformers: Robots in Disguise comic, as I mentioned last year: the Autobots, Decepticons, and "NAILs" (Non Aligned Indigenous Lifeforms, i.e. neutral Cybertronians) are trying to co-exist peacefully after their long civil war. More generally, I think that various comics have done a good job of exploring this concept.
Spoilers follow for Swamp Thing, Animal Man, and Lucifer.
When Alan Moore took over Swamp Thing in the 1980s, he re-invented the character as a force of nature. He also introduced the concept of "The Green": this is essentially a group consciousness for all plant life. During his first storyline (reprinted in Saga of the Swamp Thing), someone else gets access to the Green and tries to kill off all animal life. However, the Swamp Thing points out the flaw in this plan: "And what will change the oxygen back into the gases that we need to survive when the men and animals are dead?" There was a follow-up conversation at the end:
Abigail Cable: "He realised that the plants couldn't survive without man ... and so the plants backed down."
Swamp Thing: "Yes. I wonder ... will your people do as much?"
Looking at the recent DC reboot (the New 52), Animal Man introduced the idea of "The Red", which is the animal equivalent to "The Green". There was also a crossover between Animal Man and Swamp Thing, pitting them both against "The Rot". I suspect that the original idea was to call it "The Black", since all the relevant creatures are coloured that way, but they may have wanted to avoid racial overtones.
Anyway, it's easy to see the Red and Green as the good guys, since they represent life and the Rot represents death. However, that's overly simplistic: if nothing ever died then we'd have a massive population problem, and similarly we need a way to get rid of dead bodies. In theory you could avoid those problems with a fixed population, but then it would never change. I think it was one of Dawkins' books where he said that "Non-random death is a prerequisite for evolution." Looking at the comics, they explicitly said that the Rot was only a problem because it was out of control, and the three forces need to stay in balance. Looking at the current storyline, I suspect they're leading to a point where the Red gets too pushy and so the Green and the Rot will have to work together to suppress the Red. (That would also make sense given the current avatars of each force.)
Turning to Lucifer, this was a spin-off from Sandman but it's well worth reading on its own merits. In book 9 (Crux), one of the characters has literally acquired godlike powers and they create a new universe. This leads to a story told as a creation myth.
Narrator: "The people of the mark spread their dominion from the mountains to the sea. And they multiplied, and waxed numerous. Until they did cover up the land."
Creator: "Uh oh."
Narrator: "And starvation and plague fell upon them. And became their nemesis."
Creator: "It's the bugs. The ones I made to break down things that had died. They've mutated, and now they're killing people! So I'll mutate them back. I should be able to do that without ... But then the population crisis will just get worse. They'll starve, and murder each other for food."
This story had a slightly different emphasis, because it was really about the Creator learning how to use their power and also learning when not to use it. However, the same principle of balance still applies.
So, I think the point here is that forces can be opposed to each other without either of them being wrong.