But no, you don't need a legit copy for MP.

Wiring Elements:

1, 3, and 5 Second Timers - craft with 1 watch + 5 iron bars + 1 wire (thanks xTeniPurix!).
Active Blocks - craft with 1 block + 1 wire.
Inactive Blocks - craft with 1 block + 1 wire (simply reversed Active Blocks).
Explosives - craft with 3 dynamite + 1 wire (thanks Boilingfort!).
Lights - can be turned on/off if powered with few exceptions.
Doors - can be opened/closed if powered. Particularly effective with pressure plates (thanks dra6o0n!).
Dart Trap - lootable in dungeon and underground.
Lever - sold by Mechanic, lootable in dungeon.
Pressure Plates (Brown, Gray, Green, Red...) - sold by Mechanic, lootable in dungeons and underground.
Pumps - craft with 10 iron bars + 2 wires. Remember to craft both Input AND Output! (thanks Vaer!)
Switch - sold by Mechanic, lootable in dungeon.
Wire - sold by Mechanic, lootable in dungeon and underground.
Wire Cutter - sold by Mechanic.
Wrench - sold by Mechanic.

Spawn Statues (spawn element when powered):

Bat Statue - spawns a bat.
Bird Statue - spawns a bird.
Bomb Statue - spawns an unlit bomb. ~5 second cooldown (thanks Vaer!).
Bunny Statue - spawns a bunny.
Chest Statue - spawns a mimic.
Crab Statue - spawns a crab.
Fish Statue - spawns a goldfish. Works on land.
Heart Statue - spawns a heart. Works on land.
Jellyfish Statue - spawns a blue jellyfish. Works on land.
Skeleton Statue - spawns a skeleton.
Slime Statue - spawns a slime. Appears to allow only 3 at a time.
Star Statue - spawns a star. 25 second cooldown.

Teleport Statues:

King Statue - teleports random male NPC to statue location when powered
Queen Statue - teleports random female NPC to statue location when powered

Sadly no player teleport that we know of yet.

Unknown Use (other than decorative):

Angel Statue
Anvil Statue
Armor Statue
Axe Statue
Boot Statue
Bow Statue
Corrupt Statue
Cross Statue
Eyeball Statue (possibly spawn Eyes at night?)
Gargoyle Statue
Gloom Statue
Goblin Statue (does this spawn Goblins under any circumstances?)
Hammer Statue
Hornet Statue (spawn Hornets?)
Imp Statue (possibly spawn Imps when placed in the Underworld?)
Mushroom Statue
Pickaxe Statue
Pillar Statue
Piranha Statue (spawn Piranhas?)
Pot Statue
Potion Statue
Reaper Statue
Shield Statue
Spear Statue
Sunflower Statue
Sword Statue
Tree Statue
Woman Statue