Feed Station

Insert a supply of Wheat and it will automatically feed nearby animals. Apply a Redstone signal to turn it off. If left unchecked, this will duplicate your animals so much that it will probably fill up the contained space where they're kept.

Trade Station

Place in a village. Used to assist with trading with villagers. This can be crafted together with a Minecart to get a mobile Trade Station Cart.

The developer of Railcraft, CovertJaguar, has created a short video on YouTube showing how to use the Trade Station:

Force Track Emitter

Summons a laser track across a distance when supplied with enough energy. Also needs to be turned on via a Redstone signal.

Logbook

Records the name of any player that enters a 16 block radius around the Logbook, and the day they visited. The Logbook can only be removed by the player that placed it.

Smoker

Produces smoke particles which rise into the air. A Redstone signal will turn the Smoker off. Right-click the Smoker with a dye to change the color of the smoke. This consumes the dye.