I can't make up my mind whether the pennies with missing waves are truly rare and merit an entry on my Rare Penny site. Example occur for 1934, 1937, 1966 and 1967 (these are the dates that I know about) and I have pictures of fewer than 5 for each date. Although I don't regard them as a truly recordable man-made "variety", they are genuinely collectable and appear to be scarce. At first I created a web page for each year but now I have summarised them on a single page, although I am continuing to update the individual year pages and they can be reinstated at any time if collectors show the interest.
I'd be grateful to know of any other years which exhibit this feature.