What is causing the vibrations through my water pipes after flushing the toilet?
Could be that the float/valve is causing this. If you flush the toilet and hold down the float, then let go when the tank is full (you might have to pull up on the float to close the valve quickly), do the pipes vibrate? If not, replace the valve assembly. If there is still vibration I'm not sure what else could cause this (except if the tank value didn't close all the way) because there's no other active valve in the system at that time. For just $5, replace the valve assembly.