I know some of these probably been mentioned already, and some might be already in game (Barely touched some of the mechanic stuff yet); but what I would like to see is:
Laser wiring: Using lasers for something like a trip wire. That florescent mod that was mentioned earlier makes sense for this.
Drawbridge: an item like a door that is 4 blocks in length that rotates on an axle. 3 length platform like block attached to a 4th. The lengthy one will rotate around the 4th block circling it. Like your normal drawbidge it will stop when there is a block in its way.
--There could be longer variants later one made with other materials. Maybe even different styles depending on the wood used for wooden ones.
--Traps could be made with this to it will move mobs/players back in a certain direction, or be an obstical similar to those spinning balls in the dungeon, but has collision type thing that will stop it from moving.
--Constant activated current will continue its' movement to rotate around the block.
--Once current goes inactive, and activates again will rotate in reverse direction.
Ship Wheel: button is held down(mouse button) on the object it will continue to be active. The ship wheel will spin slowly to imitate that it is still being held down, and stop upon release.
--This in conjunction with the drawbidge idea above could make those drawbridge dreams come true.
--Press and hold again to reverse the rotation.
--Possibly made with a cog/gear of some kind.
Conveyors: Like what others have been mentioning to transport loose items on the ground or rather that land on it. People & mobs get pushed depending on the direction it is going if activated.
--Could work with above ship wheel or any other wiring bit.
--Mainly placed horizontally, but can be placed vertically. When vertical it does not lift mobs or players. will have visually a scoop or platform like bit to indicate items can be lifted upward.
--1x1 block that will merge to become a unison one visually when multiple next to each other, unless hammered.
--Can be done diagonally, more likely with use of hammer. This will move all entities/mobs/players in a certain direction. escalator maybe.
--Direction can be tuned on placement with player facing or hammered in. Visual arrow could be hint at direction, or some kind of indicator.
Item tubes: For if the vertical part might not be feasible on the conveyor. Made to lift items up through a tube, most likely made of glass or other material. Similar to the pipe idea mentioned, but for items/entities.
--Only moves items when active.
--Vertical movement primarily. Although could be an alternative to conveyor and add horizontal as well.
--Hammer to adjust direction. By default will go in the direction of tube it is connected to.
Lift Gate: No not mechanic logic; an actual physical lift gate. Will take up a 4x3 space most likely. Acts like a movable platform that goes up and down a short distance.
--Can help in moving NPCs upward and downward easier like a short range elevator.
--Looks like a platform between a couple posts.
--Possible taller variants with better materials, but initial wooden one will be short vertical distance. Maybe metal ones are larger vertical distance up/down.
--Only needs ground below posts, if possible.
--Only moves when activated. Like a plate or lever pushed once will move it to height. Pushed again and goes back down to bottom.
Doors & trap doors open close to wiring mechanic. If this is already the case then good; if not would be nice to wire up a door to open close on plates or other activating device, possibly adding an actuator or new type of actuator so that you can determine the direction of the door opening, if it is able.
--Mechanical doors that open up vertically, and usually made of glass or some kind of metal. Needs to have a wired activator to open, as can not open manually. (or just a variant of regular doors to function like that.)
--Way to lock them. Whether actuator or some kind of wiring.
Hoppers/dispensers: Ways to use items and transport them. Hoppers being the tansport, hammer can determine direction.
--Has small inventory like 1-4 items. Possible use in item sorting to chests.
--Chest being wire-able for this kind of purpose.
--Dispensers will shoot item placed inside. If block it will be like the antilion. Has a small inventory. Like hopper hammer determines direction of fire in an 8 directional way. 4 cardinal and 4 diagonal.
Dual Armor Mannequin: Is craftable with a couple mannequins and possibly cogs or wires. Could be more expensive, and later game craftable.
--will open up to box with armor slots, two pairs. So you can drop in exactly what you want to store. Like inventory, with vanity and armor slots.
--Will show like the character all things that appear visually.
--Inactive will show first set. Active will show second set.
--Has to be wired up to change.
Pumps: Something to transport liquids from one place to another. Visually seeing it flow from one place to another.
--Pipes to connect from one pump to the other.
--Hammer to determine flow direction.
Projectile activated buttons/switches/plates.
More statue being activatable with wiring.
That is all I can think of off hand. There are many more brilliant ideas out there I'm sure, but it is what would be nice to see among some of the other great ideas.