Earth-0 — "My" Earth, home to the JLA and others
Earth-1 — Younger JLA variants just starting out (Superman: Earth One et al.)
Earth-2 — The Justice Society of America (New 52)
Earth-3 — The Crime Syndicate
Earth-4 — Variants of the Question, Blue Beetle. Captain Atom, et al. (Multiversity Pax Americana)
Earth-5 — Variants of the Shazam family (Multiversity: Thunderworld Adventures)
Earth-6 — Wildly alternate variants of Earth-0 heroes (lust Imagine Stan Lee Creating the DC Universe)
Earth-7 — Destroyed; sole survivor. Thunderer (Multiversity #1)
Earth-8 — "Angor." home of the Retaliators
Earth 9 — The "Tangent Heroes" (DC: Tangent Comics)
Earth-10 — The Freedom Fighters
Earth-11 — Reversed-gender variants of Earth-0 heroes and villains
Earth-12 — A future Earth home to a young "Batman Beyond"
Earth-13 — An Earth based on magic rather than science; home of Superdemon
Earth-14 — Justice League of Assassins (deceased) (Superman v4 #15)
Earth-15 — Home of the Cosmic Grail
Earth-16 — Home of celebrity sidekicks the Just (Multiversity The Just)
Earth-17 — Ravaged by nuclear war in 1986; home of the Atomic Knights
Earth-18 — Frozen in Old West times; home of the Justice Riders
Earth-19 — Steampunk heroes (Gotham by Gaslight et al.)
Earth-20 — The Society of Super-Heroes, -pulp magazine"-style adventurers
Earth-21 — A ILA created during the Space Race (DC: The New Frontier)
Earth-22 — A future Earth marred by a war that claimed most superheroes (Kingdom Come)
Earth-23 — Home of President Calvin Ellis, a.k.a. Superman (Action Comics v2 u9 et al.)
Earth-24 — Predominantly female heroes fight World War II (DC Comics: Bombshells)
Earth-25 — Adventurer Tom Strong and friends
Earth-26 — The anthropomorphic Zoo Crew
Earth-27 — Dinosaur JLAers (The Jurassic League)
Earth-28 — Heroes fight using mechanized war suns (DC Mech)
Earth-29 — The backward Bizarroverse
Earth-30 — Superman's rocket lands in Soviet Russia (Superman: Red Son)
Earth-31 — Home to Leatherwmg and other "pirate heroes" (Detective Annual #7 et al.)
Earth-32 — Random combinations of Earth-0 heroes (Batman: In Darkest Knight, et al.)
Earth-33 — A world in which all superheroes are fictional (Flash #179 et al)
Earth-34 — The Light Brigade
Earth-35 — The Super Americans
Earth-36 — Optiman and friends
Earth-37 — A grim world of rapid technological advancements (Batman: Thrillkiller et al.)
Earth-38 — Older multi-generational Earth-0 variants (Superman & Batman: Generations)
Earth-39 — Agents of WONDER
Earth-40 — Evil counterprits of Earth-20's heroes
Earth-41 — Spore, Dino-Cop,, Nightcracker, and others
Earth-42 — Cute "chibi" Earth-0 counterparts
Earth-43 — A vampire Justice League (Batman & Dracula: Red Rain)
Earth-44 — Robotic JLA variants
Earth-45 — Creators of Superdoomsday
Earth-46 — A grim young Batman with a unique, unrecognizable rogues' gallery (Batman: The Gargoyle of Gotham)
Earth-47 — The Love Syndicate of Dreamworld, the inferior Five (Pres #1. et al.)
Earth-48 — Tne Forerunners, genetically engineered warriors
Earth-49 — Lois Lane dies, turning Superman dark (Injustice)
Earth-50 — The tyrannical Justice Lords
Earth-51 — An accelerated timeline where Earth met with a Great Disaster and is ruled by talking animals (Kamands, the Last Boy on Earth #41 et al)
Earth-52 — The Primate Legion, sapient metasimians
Earth-54 — Humankind lands on Mars in 1960; Earth of astronaut Tommy Tomorrow
Earth-55 — Zombie versions of Earth-0 heroes (DCeased)
Earth-59 — Home of Wonder Woman Tan Terruna (Note• first known parallel Earth) (Wonder Woman v1 #59)
Earth-63 — Overrun with vampire counterparts of Earth-0 heroes (DC vs. Vampires)
Earth-66 — Batman and Robin face exceptionally benign villains (Batman '66)
Earth-93 — The Dakotaverse (Icon #1 et al.)
Earth-96 — Teenage students Batgal, Bumblebee, Supergirl, Zatanna, and others (DC Super Hero Girls et al.)
Earth-98 — Home of Green Lantern Tai Pham (Green Lantern: Legacy)
Earth-100 — Home to Teen Titans Raven Roth, Garfield Logan, Damian Wayne, and others (Teen Titans: Raven et al.)
Earth-118 — Medieval versions of Earth-0 heroes (Dark Knights of Steel)
Earth-124 — Home to Wonder Woman. Wonder Girl, and Wonder Tot (Wonder Woman v1 #124)
Earth-148 — Earth-0 counterpart heroes are villains and vice versa (World's Finest Comics v1 # 148 et al.)
Earth-162 — Superman and later, Batman divided into two separate beings (Superman v1 #162)
Earth-183 — Superman raised by apes (Superboy #183 et al.)
Earth-216 — Home of Superman. Jr. and Batman, Jr. (World's Finest Comics #215, et al.)
Earth-387 — No divergences in history other than every inhabitant is a werewolf (Adventure Comics #387)
Earth-789 — Superman and Supergirl are Earth's only powered heroes; Batman's parents killed by the joker. (Superman '78, Batman '89)
Earth-898 — A Justice League without a Superman (JLA: The Nail)
Earth-1956 — A teenage Superman (Superboy) and his dog, Krypto, are Earth's first super-heroes; later, home of the Super Friends
Earth-1996 — Mysterious "amalgamated" (?) heroes; requires further investigation?
Earth-2020 — Three generations of Supermen (Superman v1 #354 et al.)
Note: the list is not comprehensive: is a number isn't listed, that doesn't mean that an Earth doesn't exist in that spot. Quite the contrary; one can assume that every natural number has an Earth; we just haven't been told what's in the spots that have been skipped.
[EDIT: we have now been shown two of those.
Earth-247: home of the post-Zero Hour Legion of Superheroes.
Earth-1993: home of the original Dakotaverse.
/EDIT]
The first 52 Earths are identical to Morrison's Multiverse, but with the “seven Unknown Earths” filled in. The later numbers are either made up out of whole cloth, based on the issue number that they first appeared in, or based on the year that they first appeared. This is similar to the scheme used to catalog many pre-Crisis Earths; so it would be safe to say that world numbers catalogued in Crisis on Infinite Earths: Absolute Edition which don't conflict with this list exist, and are still the same. In fact, some of these new Earths are the same as their pre-Crisis counterparts, as far as I can tell: they are Earths 54, 59, 124, 148, 162, 183, 216, 387, 898, and 2020. Pre-Crisis numerical designations that haven't been claimed in the new Multiverse and haven't been renumbered are: Earths 57, 64, 85, 89, 91, 95, 116, 117, 127, 132, 134, 136, 146, 149, 154, 159, 166, 167, 170, 172, 175, 178, 184, 192, 200, 215, 224, 230, 235, 238, 265, 270, 276, 300, 332, 353, 377, 383, 388, 391, 395, 399, 404, 410, 417, 423, 462, 508, 523, 677, 686, 702, 922, 988, 1098, 1099, 1101, 1163, 1198, 1289, 1863, 1876, 1888, 1927, 1938, and 5050.
Two original Multiverse Earth's deserve special attention: Earth 235 is the designation given for the Realworlds fifth-week events, which could either stand on its own or be folded into Earth 33; and Earth 247, while not on this list, has been confirmed as part of the new Multiverse in teasers for the upcoming Legion of Four Worlds.
The worlds that aren't numbered, or that have numbers that conflict, are more questionable: in theory, the Infinite Earths has room for everything, and you merely need to assign a new natural number to each of those Earths (e.g., pre-Crisis Earth 2 might now be Earth-1961, based on the year that Flash of Two Worlds was published); but in practice, “Infinite” isn't the same as “Everything”; and some of those “orphaned Earths” may be completely absent from the Infinite Earths. Non-numbered Earths are: Earths C-minus and C-plus, D, G, I, Q, Quality; I-Earth, M-Earth, and R-Earth; Earth-Terra, Jimmy Olsen's Earth C, and Crossover Earth.
The “archived Earths” from Doomsday Clock aren't listed here. My pet theory is that they're on the Hypertime side of the Divine Continuum; the way they spawn whenever Earth 0 changes matches the way Hypertime operates, and it means that we don't have to find places for them in the Omniverse. More generally, I'd also be inclined to put other “Earths” that are either “altered histories” (e.g., “Earth B”, the world that resulted from an evil Johnny Thunder messing with the timeline to replace the JLA with criminals) or “possible futures” in Hypertime instead of assigning “vibrational signatures” to them.