I'm on a roll this week. I've added fishing boats and catapults.
Fishing boats will kind of act as mobile food producers. They will give a 25% chance of food for each adjacent empty pure water tile. This should give a non military incentive for building lakes, rivers, and oceans. They have 1 hit point and will do no damage in combat.
Catapults will finally make it easier to get through enemy walls and buildings. They have 1 hit point and will do no damage to other units. If used to attack a structure such as a wall or capital, they will do 10 points of damage each attack. Right now you have to move right up on your target to deal damage with catapults, but once I've implemented ranged attacks - they will be able to attack structures from a few tiles away.