i'm in a pirate game and one of the pc's has a queegish cohort. he's a ranger specializing in missile attacks and uses a harpoon. the player and dm worked on stats for a harpoon because they couldn't find one they liked.

Stormwrack may also have some ideas for you on this. I think a ranger/rogue character would work well.

well i got a chance to look at stormwrack today too, and it does indeed have a harpoon. it's wicked nasty.

Ranged Weapon, 15 gp, 1d10, x2, 30ft range, 10lbs, piercing

"If it deals damage, the harpoon lodges in an opponent who fails a Reflex saving throw (DC 10 + damage dealt) A harpooned creature moves at only half speed and cannot charge or run. If you control the trailing rope by succeeding an opposed Strength check while holding it, the harpooned creature can move only within the limits that the rope allows (30 feet). If the harpooned creature attempted to cast a spell, it must succeed on a DC 15 Concentraion check or lose the spell.
The harpooned creature can pull the harpoon from its wound if it has two free hands and takes a full-round action to do so, but it deals damage to itself equal to the initial damage the harpoon dealt. A character who suceeds on a DC 15 Heal check can remove a harpoon without further damage." -Stormwrack, pg 107