Minecraft wiki entry for Redstone_mechanics, associated text: Impulse Command Block (also produces comparator updates)
Repeating Command Block (also produces comparator updates)
Chain Command Block (also produces comparator updates)
Dispenser (also produces comparator updates)
Dropper (also produces comparator updates)
Doors
Fence Gates (can be moved)
Hopper (also produces comparator updates)
Redstone Lamp (can be moved)
Trapdoors (can be moved)