I think the Eberron setting has some of the best ideas, for what druids "role" can be, in the concept of druid sects. This makes them more than just neutral guys obessed with "the balance" who digs nature .
Ashbound: These are the eco terroist types, ranging from giving a stern talking to a farmer, to "burn his house and fields and let nature grow back". They generally hate magic that is not druidic and considers agriculture, animal husbandry and other trappings of civilazation to be "unatural".
Children of Winter: These guys believe that it is time for a change, the current world should end so that a new can blossom in its stead. They like to use the darker druid magic; poison, disease and vermin companions and wildshapes.
Basically evil druids with some philosophical underpinnings to justify their emo-ness :-P
Gatekeepers: My personal favorite, they are and ancient order who learned their craft from a great black wyrm thousands of years ago (You cant trust the color coding of dragons in Eberron). Keeping abberations, outsiders and other unatural otherwolrdly things out of thier world. These are tied a bit closer to the Eberron setting than the others, as planar incursions is a common problem in that setting.
Greensingers: These are the guys that like to "frolic" around with fey and can be very chaotic, a more mystical and primal form of nature worship. They dont have much contact with the civalized world.
And finally the Wardens of the Wood: These are the "vanilla" druids that often lives on outskirts of communities and help out when there are clashes between nature and civilization and these are the closet to the "balance" druids.
These sects can easily be tranplanted to any setting or just used as general guidelines for your druids outlook on life