RPing druids tends to be hard for a lot of people; for some reason they tend to end up either stereotypical granola eating hippies or radical ecofreaks. I've no idea why.
Here are some less common adventuring druids:
The atavist: this druid is likely to pick up one of the shaper PrCs because they really get into wildshape. They try to follow their animalistic instincts as much as possible. This can result in some disturbing things, like eating the flesh of a sentient race. Atavists tend to be quite civilized when not wildshaped, seeing that as the dominant trait of the sentient races. The atavist adventures so they can experience a wider view of the world both as their normal race and as various animals. Atavists *love* the "alter self" ability at higher druid levels. They tend to be more attack & stealth oriented than most druids so parties can appreciate them.
Caller of animals: this summoner is the guy who talks to horses before buying a new mount, uses his wolf companion to see if the innkeep is cruel to the guard dogs, and tends to summon creatures that are appropriate for the environment. A Caller is more likely to heal a soldier's mount than the soldier. Callers will often pick up the Turn Animal feat and love nothing more than breaking a cavalry charge with a single word since it saves the horses' lives. Animal friendship/charm spells are used a lot in concert with critter buffs.
Force of nature: this druid is a "big picture" druid who embraces the power of the sun, the vibrance of the forest, the thrill of the snow, the solidity of the earth and the thunder of wind. They use weather spells to confuse foes, plant spells to contain them and elemental spells to anhiliate them. Nature druids speak to stones, the wind (commune w/nature), the forest and they all obey. Forces of Nature tend to think of themselves as the "spotter" for nature's righteous fury but occassionally mix it up. Flame blade is an oft-forgotten spell that's touch-attack nature offsets the druid's BAB.