Melee: The Druid can Wildshape and tangle up with foes, and has the ability to heal himself passably well.
Healing: Not as good as the Cleric, but he can prepare Cure spells, and Wildshape heals himself.
Scouting: Again, Wildshape is key here, and he can become a fairly innocuous rat in urban environments, or a hawk in natural ones. As such he is generally undetectable by enemies because he is in plain sight. Nature Sense gives the Druid a slight edge over the Ranger in Survival, as long as it's not about tracking Favored Enemies.
Support Spells: The Druid has some great buffs, and while Summon Nature's Ally doesn't have the punch that Summon Monster does, he can do it at a whim. He has the best caster's anti-melee abjuration in the game in Anti-life Shell. Can Scry for "free", and pretty much anywhere.
Attack Spells: These don't really come into their own until the higher levels, but when the Druid reaches 5th level spells he starts laying the hurt down. If you are skeptical, read Sepulchrave's story hour... in it you will see a single druid laying waste to an Army with strong clerical support.
Skills: Outdoorsy in nature, but they arn't bad; Listen and Spot go a long way, specially for casters. And while Clerics, Wizards and Sorcs languish under 2+INT for skills, the Druid has a nice 4+.
Information Gathering: In natural environments the Druid is the best info-gatherer in the game, what with Stone Tell, Speak with Animals and Speak with Plants. In urban environs, he has Diplomacy as a class skill, and the role-playing advantage of being able to say that he represents Nature... and that Nature is something the urbanites don't want to upset.
Character Interaction: Again, the Druid can rely on Diplomacy to help here. It won't be as powerful because the Bluff, Sense Motive and Know (royalty) skill are cross-class, but it can be strong. The Druid's spell list does not help much here. It's campaign specific, but a society of druids is common, and a built-in support for the Druid character.