Pre-Crisis Alternate and Unnamed Earths

There are and always have been parallel Earths and dimensions that have been the focus of a single story or a plot device. The list below is the result of an e-mail from Michael Norwitz who suggested a number of additions to the Atlas and supplied the information for the following. Many of the Earths described would be the basis for what DC would come to call Elseworld stories.

The Earth visited by several members of the JLA and the LSH, and later by Jimmy Olsen. It featured a non-powered, living Jor-El and an otherwise nonpowered Kal-El who was a shapechanger and a master spy. On this Earth, social status is granted by the wearing of a cape; those not wearing capes are treated as slaves.
Earth-T, home of the Captain Marvel counterpart Captain Thunder (Willie Fawcett), from Superman circa 1974. One could arguably claim this Earth for other divergent Fawcett heroes, including the Spy-Smasher who changed his name to Crime-Smasher at the end of the war (which he hadn't seemed to when the Earth-S hero appeared in the JLA); one of the many Captain Midnight versions; the Ibis who was not vulnerable to black magic; the Kid Eternity who was bodily displaced by the heroes he summoned; and the Bulletman who cavorted with Atomic Man and Eagle-Eye G.I. Joe.
The Earth mentioned in Animal Man with hippified heroes, including Sunshine Superman, Speed Freak, and Magic Lantern. One could arguably claim this Earth for the Prez series from the 70's; if so, there may be textual evidence this Earth also has a Wildcat.
There were three different Earths shown in which Superman was raised by the Waynes instead of the Kents. One of them actually had different continental patterns, and in it Bruce (Superman) Wayne had as a sidekick a nonpowered Robin, and was friends with Commissioner Gordon, Vicki Vale, and Alfred Pennyworth; a man named Freddy Forbes, an exact lookalike for the Joker, was a TV star. Another one of these Earths had Superman inspiring Barbara Gordon to become the non-powered Batgirl. The third of these, with sadly little connection with the other two, appeared in the Elseworlds book "Faster Than A Speeding Bullet".
The Earth in which Lois Lane was the superpowered Krypton Woman, and Clark Kent a mild-mannered reporter who eventually discovered her secret identity by exposing her to Red Kryptonite.
The Earth in which Superman's parents came to Earth as infants; Lara became Superwoman. They did eventually discover their origin, and that despite their original fears they were not brother and sister.
The Earth in which Superman was raised by Germans and started his career in the 30's battling such foes as Nosferatu, 'M', Dr. Mabuse, and the evil scientist Rotwang; from Kim Newman's short story "Ubermensch".
The Earth in which Superman was bald and resembled Lex Luthor, and Clark Kent was a human criminal (this could be the Mirror Earth, but it is incompatible with the Earth with the evil Superboy who battled the LSH whom I also mentioned as a possibility). It was a very dark, well-written story.
The Earth in which Kara Zor-El came to Earth first, established herself as a heroine, and then took on the newly-arrived Kal-El as a partner and "secret weapon". Their costumes were identical to Superman's and Supergirl's but their named featured different superlatives with correspondingly different letters in their chest symbols.
The Earth of Luma Lynai (A Supergirl/ Power Girl like heroine from an alternate dimension. She had a white costume like Power Girl's and was fringed in green).
Finally, there was an issue of Batman in which he saw counterparts of himself based on varied other animals ... an owl, a deer, etc.