Shiftable Spawners
You can shift mob spawners one block from their current location by breaking them with a silk touch golden pickaxe. This will also cost whatever experience the spawner would have given you, a random value between 15-43 points.
When broken, it will pick a block within a 1 block radius cube around the spawner. It will never shift on top of itself, and requires that the location it shifts to have a supporting solid block and be air.