off the top of my head....
...rework the entire system to be an on/off state rather than toggling puleses? kidding. more realistically now:
-wiring relay(if one wire is activated the others touching this item are too. it connects different wire colors)
one block size
--disabled by deactuation
-directional wiring item(wire signal will pass one way but not the other)
2 block size(one tile in, other tile out...assuming it can be made to "cut" wires so wires of the same color don't connect...if not then it'd have to be either 3x1 blocks(middle inert) or 2x2(left half is in, right is out))
-delay timers(receives signal, counts down and then sends the signal to any wires touching it. lets you set up time delays) comes in 1,3,5 varieties.
-wireless wiring. an item to let us send/receive signals with a beam.
--is obstructed by blocks, requires line of sight.
--one item to generate the beam, another to receive it.
--signal passes both ways when connected
--picturing a satellite dish you hammer to change direction, and an antenna. (beam cosmetically similar to gemspark waterfalls?) items are statue sized, sends a one block sized beam.
--cuts down on tedium of laying wire over long distances
--another item to bounce the beam along right angles(hammer to change direction, 1 block size, doesn't work when deactuated)
-actuating wand(toggle this block i clicked into its actuated/deactuated state)
-color specific actuators(ex red actuator activates only from red wire, ignores signals from blue or green wire) for each wire type
-damage switch(remember the crystals we had to attack in zelda? those)
-countdown timer: a third sort of timer so upon receiving a signal something is active for [1,3,5] seconds and then shuts itself off(so in terraria's wiring system that means: gets and forwards a 'pulse' and then after the timer runs sends another one)
-another kind of pressure plate that is active as long as it is being held down rather than a toggle(translated to "terraria's wiring system" it becomes "step on it sends a pulse, stepping off it sends another")
--is triggered by anything
-more traps(ex: a trapdoor that automatically opens when stepped on, conveyerbelt tiles, a gate that locks itself when powered, ect)
-more statues that interact with wiring(firefly statue, wolf statue, make pickaxe buff mining and sword statue buff melee, shield buffs defense in its area, sunflower glows like mushroom does ect)
-wire spool: building accessory, places wire as we walk
-multiwrench(let us place any wire color. right click to change? maybe even include the wire cutters)
-remember active/inactive timers the way the game remembers fountain and torch activation
-liquid sensor switch(sends pulse when wet/dry)(probably can use the existing function that turns off the water pump)
-light sensor(if possible. like a torch is brought close enough it triggers)
-not really wiring persay but lockable doors that require a key of the same color to open(i already ended up listing conveyerbelt as a trap so whatever. close enough right?
)
-potion to view wires
-undo change to statue activation points? ;P
-not sure how but something we could use to let us only turn items on(and another for off) rather than just toggle the state