Frankly we could have a 'Beatles Song of the Week' in itself such is the volume and range of music they produced, much of it original and brilliant.
'Rain' is a startling example, not least because it was a vinyl B-side, i.e., considered the inferior of the two songs on the single (the A-side was 'Paperback Writer'). Yet, from Ringo's opening drumbeats to the innovative use of backwards vocals at the end via the overall psychedelic sound, this remains exciting and modern.