Well, I have an idea, but it requires you to get it past your DM.
In E6, my favorite build is the Dungeon Crasher Fighter with Knockback and the works, because for its level the damage is quite brutal.
What you do is....
Gah, never mind. There's Ranged Pin, Disarm and Sunder, but not ranged Bullrush.
My thought was that if you were flying, you could somehow throw your Harpoon at the enemy below you into the ground, causing Dungeon Crashing damage. Then you'd use Brutal Throw and just put as many points into STR as possible.
Actually, let's see here. Brutal Throw, Power Attack, Power Throw, Improved Bullrush and Knockback would work. But you'd have to be Large Sized or have Powerful Build. Throw using STR, take at least -1 with PA, activate Knockback. Knock into ground, do damage +8d6 + 3xSTR.
I usually do this with a Goliath and in melee, so I don't know how it can be done here properly.
Actually, that won't work either. Knockback activates upon PA usage and Power Throw is a separate ability, not just "PA on ranged attacks" even though that's how it works. Never mind then.
Going with Dexterity to damage, consider this:
In Dragon Compendium, there is a feat on page 95.
DEAD EYE [GENERAL]
Your precision with ranged weapons translates into more telling strikes than you could normally make.
Prerequisites: Dex 17, Point Blank Shot, Weapon Focus (any ranged weapon), base attack bonus +14.
Benefit: You may add your Dexterity bonus on damage rolls made with ranged weapons for which
you have the Weapon Focus feat, so long as the target is within 30 feet.
Special: Dead Eye does not increase the damage dealt to creatures immune to critical hits.
A fighter may select Dead Eye as one of his fighter bonus feats.
Author: Clifford Horrowitz. Source: #304.
NOTE: As per the errata, the BAB requirement drops from a staggering +14 to a minimal +1.