One tactic that I used for my druid while he was still at level 5-9 was spell casting while aerial (thanks to natural spell). Depending on what resources you have, the druids spell arsenal can be far larger than normal. The Miniatures handbook has several excellent spells, including a pounce spell that can work wonders for a melee oriented druid, while there are several electrical and energy spells that work well also.
Masters of the Wild also has several good spells. If you have it, the regeneration spells work wonders, as long as they are cast beforehand.
If the party is outside, in cloudy/stormy weather, then call lightning works wonders, esp from mid-air. If the druids have metamagic rods (empower or maximize) then the damage would be far higher. The Mini's HB also has Sudden metamagic feats that would allow spells to be spontaniously meta'ed once daily, which works wonders for a greater call lightning at level 9 on a cloudy day (50 damage every round for 9 rounds hurts a lot).
Animal companions can work wonders to create flanking situations as well, which may help out Druid/Rogues (or what have you). Dire Wolverines make an excellent choice, since they have rage powers, and Dire Weasels have con-drain abilities also.
Altering the environment to fit the battle is the druids focus. From simple entangle and briar webs, to sleet storm, snare, spike growth/spike stones (slows down tank fighters lots), and the all time favorites like transmute rock to mud, wall of thorns and so on. Multiple druids working together to alter the fighting zone first, then starting out with damage is a huge benefit, especially against melee oriented fighter types.
Using similar tactics, my lv 12 druid was able to alter a fighting zone so much that my adventuring party (6 of us) destroyed 10 fomorian giants (15HD each) and their dire animals without any damage recieved in return. However, that was only due to their utter lack of ranged attack ability; which if they had, then things would have been worse.